[SOLVED] I'm looking for Sendo M570 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my Sendo M570. 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.

@Yvonne

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 Sendo M570 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/run-gear-vr-without-connecting-to-headset.3825897/
Take a look at comment #16
Also, this : https://xdaforums.com/t/tcpmp-doesnt-work-properly-with-wm6.290563/.
You can also check this video starting from minute 8:

The Sendo M570 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 Sendo M570 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 Sendo M570 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 Sendo M570 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/new-note-5-user.3395975/

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

Avoid Liquids: Protect your phone from liquid exposure, which is a major cause of corrosion and component failure. After a year or two, due to chemical degradation, that same battery might only be able to hold 2500mAh, even when it reports 100% charged. Replacement Coaxial Cable(s): Obtain genuine OEM or high-quality aftermarket parts specific to your phone model. Clean Screen: Ensure the screen is meticulously clean, free of smudges, fingerprints, and dust. Separate Panels: Carefully slide the plastic pry tool around the perimeter, reheating areas as needed, to fully separate the panel. This requires specialized software (e.g., a custom Python script or specific toolboxes in MATLAB). Causes can range from physical impact, liquid damage, or simply the wear and tear of a tiny mechanical part over time. Connect a new or known-good display flex cable to the newly installed connector. Disconnect Battery (again): Always disconnect the battery before completing reassembly. Wi-Fi Analyzer Apps: Use apps (e.g., "Wi-Fi Analyzer" on Android, various third-party apps on iOS) to visualize Wi-Fi signal strength (RSSI), channel congestion, and identify potential interference. Waterproofing Disclaimer: If the device was originally water-resistant and you've resealed it, clarify that you cannot guarantee the original IP rating. The goal is to soften the adhesive, not melt the plastic or damage internal components. JTAG/eMMC/UFS Programmers: For direct access to NAND/eMMC/UFS memory on the motherboard, tools like Medusa Pro II, EasyJTAG Plus, or Z3X JTAG Box are used. Open the Phone: Depending on your phone model, this will involve either removing the back cover or detaching the display assembly. Using a small amount of 99% isopropyl alcohol on a lint-free swab, carefully clean the contacts on both the flex cable and the motherboard connector. A stuck pixel occurs when one or more of these sub-pixels remain "on" continuously, displaying its base color regardless of the input signal. It translates the electrical signals from the digitizer grid embedded within the display assembly into digital data that the main processor can understand. Always connect the oscilloscope's ground lead securely to a known ground point on the motherboard, such as a shielding can or a large ground plane. Apply strong, clear packing tape or specialized screen removal tape in a criss-cross pattern over the entire surface of the shattered display. You might also hear the charging sound chime on and off, or feel the phone vibrate repeatedly as it attempts to connect and disconnect. Diagnostic Apps: Many Android phones have built-in diagnostic modes (e.g., dial `#0#` on Samsung phones and select "Sensor"). Backup your data: Before any significant troubleshooting or a factory reset, always back up all important photos, contacts, and app data. Component Sourcing: Finding genuine, compatible DSPs can be difficult. Attempt to Enter Special Modes: This is the most crucial diagnostic step. However, a successful repair can save a device that would otherwise be deemed unrepairable, making it a highly rewarding endeavor for experienced technicians. Security: Keep inventory in a secure, access-controlled area to prevent theft and unauthorized handling. Systematic Approach: Always start with the simplest checks (network, software) before moving to complex hardware diagnostics. Exacto Knife or Razor Blade: For trimming adhesive or precise work (use with extreme caution). The symptoms of an overheating storage chip often overlap with other issues, making a precise diagnosis difficult without advanced tools. Desiccants: Include small packets of silica gel (often found in new product packaging) inside sealed containers to absorb moisture.

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