[SOLVED] I'm looking for M-HORSE M15 Pro max repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my M-HORSE M15 Pro max. It's started acting up, and I'm looking for a detailed service manual with boardviews and schematics to properly diagnose and repair it. I need to take precise voltage measurements around the board, so having the right documentation would be very helpful.

Thanks in advance for your help.

Selected Answer

I actually found that service manual on a tech Discord server a while back. A really helpful member there shared a direct link to their blog and I've saved it. I'm happy to pass it along here. Hopefully, these boardviews and schematics help you fix your phone, just like they got me through my repair. Looks like we have the same model.

@Zuzana

Absolute legend! That's exactly the info I was searching for. This is going to save me so much time probing in the dark. Seriously, thanks a ton for sharing the link!

Hi there,

I also have the M-HORSE M15 Pro max and just downloaded the manual you shared. I'm pretty new to board-level phone repair, and this is a bit intimidating with all the tiny test points and the schematics. Could you point me in the right direction on how to start troubleshooting this ? Any advice on the first few things I should check would be a massive help.

Thanks so much for your time

General advices: start by checking the voltage at the battery connector on the board. With a known-good battery connected, you should see a steady voltage between 3.7V and 4.2V. After that, a great next step is to check the main power management IC (PMIC) for shorts. Using your multimeter in diode mode, check for shorts on the large input capacitors surrounding the PMIC.

Here are a few useful references for troubleshooting your device:
https://xdaforums.com/t/redmi-9-random-freezes-and-reboots-with-any-rom.4757835/
Take a look at comment #1210
Also, this : https://www.ifixit.com/Answers/View/621040/My+screen+has+a+weird+looking+blot.
You can also check this video starting from minute 3:

The M-HORSE M15 Pro max service manual and boardviews from the link above were exactly what I've been searching for. I couldn't find a complete, free copy anywhere else. Seriously, thank you for sharing this you're a lifesaver!

Hi everyone, I'm working on a M-HORSE M15 Pro max with a no power issue and need some guidance with my measurements.
I'm detecting 3.3V on the VREG_MAIN line (pin 1 of the PMIC), which looks good, but I'm getting 0V on the VDD_CPU line (pin 8) where the schematics indicate I should see about 0.9V.
Since this is a core voltage for the application processor, could this missing rail be why the device shows no signs of life?
What's the best procedure to diagnose this further? Should I check for shorts on the CPU rail first, or look at the PMIC's enable signals?
I've already verified the main 3.3V and 1.8V power rails are present and stable.

My M-HORSE M15 Pro max was working perfectly until yesterday when it suddenly went completely dead. Now it won't respond to the power button, doesn't vibrate, and shows no signs of life even when connected to a charger. I'm worried there might be a serious issue.

I have a decent multimeter, a basic soldering iron, and a healthy dose of patience. While I've successfully replaced iPhone batteries and charging ports, this will be my first attempt at actual diagnosis. The sheer density of BGA chips and microscopic components is honestly a bit overwhelming.

I'm particularly curious about the alcohol trick I've seen online where you apply isopropyl to the board and look for evaporation hotspots to locate shorts. Is this actually a reliable method for beginners, or are there better approaches I should try first with just a multimeter?

I learned this lesson the hard way last month with mine, it was declared "dead" by two different shops. The phone showed absolutely no signs of life - no charging indicator, no vibration, nothing. Before diving into complex board work, I decided to try one more basic test: wireless charging.

To my complete surprise, it actually heated up on the charging pad! This single discovery completely changed my diagnostic path. It turned out the issue wasn't with the main board or processor, but with the notoriously fragile USB-C port that had failed completely. A $15 replacement part and some careful soldering brought it back to life.

The moral? Always exhaust every external testing method before opening the device. Test wireless charging if available, try different charging methods, and don't assume the worst case scenario. Sometimes the most "dead" devices have the simplest solutions hiding in plain sight.

I suspect my issue might be related to that cheap, third-party fast charger I used at the airport last week... Now the device gets extremely hot during charging, the screen flickers at low brightness, and sometimes it randomly shuts down at 30% battery. Could this have damaged the power management IC or battery calibration?

If your M-HORSE M15 Pro max starts acting up, random reboots, fast battery drain, or connectivity issues, there are several diagnostic steps you can take before assuming the worst:

• Check your charging habits: Using poor-quality chargers or wireless pads can gradually damage your battery and charging circuit, leading to unpredictable behavior.
• Inspect the physical components: A slightly damaged charging port, worn battery, or even accumulated pocket lint can cause issues that seem like major hardware failures.
• Monitor temperature patterns: If your phone gets unusually hot during specific tasks (like camera use or gaming), it could point to a failing component rather than a software issue.
• Use diagnostic tools wisely: Ampere for battery health, phone diagnostic codes (*#0*# on many models), and a thermal camera can reveal problems without opening the device.
• Know when to stop: If you see liquid damage indicators tripped or smell burnt electronics, it's time to consult a professional before causing irreversible damage.

Also visit this link it may help : https://xdaforums.com/t/just-ordered-evo-3d.1850401/

Here's what I discovered on forums and technical databases:

Look for any visible signs of damage: bends, tears in flex cables, corrosion (often indicated by green or white residue), or loose connections. If it's unusually hot, allow it to cool down completely before attempting further steps. Common symptoms of a faulty loudspeaker include distorted or crackling audio, extremely low volume even at maximum settings, intermittent sound, or a complete absence of sound. While it requires practice and a meticulous approach, the diagnostic capabilities a multimeter offers are essential for advancing your repair skills and restoring functionality to seemingly dead devices. It dynamically adjusts the charging rate based on battery temperature, state of charge, and input power capabilities. Once you have unequivocally confirmed that the new display and its flex cables are fully functional, you can proceed with the final reassembly. Among the various techniques, using "split hot air" stands out as a sophisticated method for safely desoldering Ball Grid Array (BGA) and other surface-mount components, especially when surrounding components are sensitive to heat. Some phones have hidden diagnostic menus (e.g., #0# on Samsung) that allow direct testing of the ALS. Non-Metallic Pick: Gently dislodge compacted lint with a wooden toothpick or a plastic dental pick. Use a non-conductive tool (like a plastic spudger or toothpick) to carefully remove any visible lint or dirt. If using solder wire, you can "tin" each pad lightly with fresh solder. OEM Unlocking (if necessary): For some devices, especially if you were previously rooted or using a custom ROM, you might need to enable "OEM Unlocking" in Developer Options. Prying: Use a suction cup and thin prying tools (plastic first) to carefully separate the component. It’s important to differentiate between a damaged camera module and a cracked external camera lens cover. Start with the simplest solutions, as they often resolve the issue without data loss. It demands precision, a steady hand, specialized tools, and a good understanding of micro-soldering. Screwdrivers: While metal-tipped, ensure their handles are made of ESD-safe materials. Disconnect the Battery: Locate and disconnect the battery flex cable from the motherboard immediately. If a device was factory reset without first removing the Google account, it will require the credentials of the last Google account synced to it. Downloading the correct firmware: Obtain the official firmware for your exact phone model and region from the manufacturer's website or trusted community sources (e.g., XDA Developers). If both speakers are in phase, the thump will sound solid and impactful. Damaged/Torn NFC Antenna: Is the flex cable torn? Are the antenna traces corroded or cracked? Damaged Battery: A severely degraded, failing, or swollen battery might not be able to provide enough stable power for the phone to boot fully, especially during the power-intensive startup sequence. Check Continuity from Connector to Display Flex: If you suspect the flex cable itself, carefully probe specific pins on the motherboard connector and the corresponding points further down the display flex cable to check for breaks in traces. Ultra-Thin Bezels (Especially Bottom Bezel): This is the primary driver for COF adoption. By systematically going through these diagnostic steps, from software checks and environmental considerations to detailed hardware inspection, you can accurately analyze and pinpoint the root cause of smartphone magnetometer faults, leading to effective repair or replacement strategies.How to detect smartphone EMI interference issues Benchmarking Tools: Tools like AndroBench can measure read/write speeds. Keep track of all screws, noting their original positions as they can vary in size and type. Precisely controlled hot air (temperature and airflow) for safely removing and soldering surface-mount components (ICs, connectors). Pentalobe (for iPhone), Phillips, or Torx Screwdrivers: The specific tiny screwdrivers needed for your phone model.

@Lucas, Not sure what you're trying to say but ok :)