[SOLVED] I'm looking for Verykool s4008 Leo V repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my Verykool s4008 Leo V. 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.

@Ferhat

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 Verykool s4008 Leo V 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://www.ifixit.com/Answers/View/269261/Microphone+NOT+working+in+loudspeaker+only
Take a look at comment #1101
Also, this : https://www.ifixit.com/Answers/View/599703/Acting+very+erratic+had+to+reinstall+OS+still+problematic.
You can also check this video starting from minute 8:

The Verykool s4008 Leo V 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 Verykool s4008 Leo V 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 Verykool s4008 Leo V 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 Verykool s4008 Leo V 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://www.ifixit.com/Guide/Grace+Digital+Mondo+Navigational+Knob+Replacement/59663

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

Check for any "Do Not Disturb" or "Battery Saver" modes that might disable vibration. Diagnosing and fixing this requires a systematic approach, starting with the easiest checks before delving into more complex hardware issues. Identify High Spots: Locate the exact "high spot" or bulge that needs to be pushed in. Identify and Uninstall: If Safe Mode resolves the issue, exit Safe Mode and start uninstalling recently installed apps one by one, testing the navigation bar after each uninstallation until the culprit is found. Does the computer recognize it (e.g., make a connection sound, appear in File Explorer or iTunes/Finder)? If so, the phone is on, and the issue is likely the screen. This can sever the internal conductor or shield, causing significant signal loss. Faulty Audio DAC/Amplifier Chip: The Digital-to-Analog Converter (DAC) or audio amplifier chip on the phone's motherboard might be failing or introducing noise. Gentle Straightening: Using ultra-fine tweezers or a very thin dental pick, carefully and slowly attempt to straighten the bent pin back into its correct alignment. Overheating can lead to accelerated battery degradation, damage to internal components, and in severe cases, pose a fire hazard. Remove Old OCA: Carefully scrape off all remnants of the old OCA adhesive from the LCD surface using a plastic razor blade or a specialized OCA remover liquid. Precision Screwdriver Set: (Pentalobe, Phillips, Tri-point, etc., specific to your phone model). Ball Grid Array (BGA) components are ubiquitous in modern smartphones, from the CPU and NAND storage to the PMIC (Power Management IC) and smaller controllers like the Tristar/Hydra IC. This can sometimes resolve software glitches that might be preventing the backlight from turning on. Image Signal Processor (ISP): While often integrated into the main SoC, some advanced camera systems might offload specific tasks or complex algorithms to a dedicated ISP for features like computational photography, multi-frame noise reduction, or real-time HDR. Repeat, gradually increasing the voltage (in 0.1V increments) and current limit if necessary, being very cautious about heat. Look for burnt spots or discoloration, suggesting an electrical short. Physical Impact/Drops: While protected, severe impacts can sometimes jostle or sever connections on the flex. Drops/Impacts: A severe drop can dislodge internal components, crack solder joints, or damage integrated circuits (ICs) like the CPU, RAM, or storage chip. Localized excessive heat around the PMIC area is a strong indicator of its failure. Physical Damage/Impact: Drops or impacts can physically damage the antenna itself, its internal components, or its delicate connectors and flex cables. A faulty ambient light sensor could cause erratic brightness, leading to perceived flicker. Reassemble the rest of the phone, ensuring all screws are in place and flex cables are properly connected. Internal Layers: Sandwiched between the outer layers are internal signal layers and power/ground planes. Water/Impact Damage: Look for signs of water ingress (green/blue corrosion, white residue) or physical impact (dents, cracked components) around the antenna connections and the general RF section of the motherboard. If you removed the display or rear glass, apply new adhesive strips or a thin bead of B-7000 adhesive to ensure a strong seal and maintain water resistance. Carefully pry open the device using a suction cup and plastic opening tools. Understand that these ratings are for freshwater under controlled lab conditions. Check alignment, especially around camera cutouts and button openings. Properly applying new adhesive tape during smartphone reassembly is not merely a final step but a crucial part of a successful repair. Internal Hardware Inspection (Requires Opening the Phone): Proceed with caution.

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