[SOLVED] I'm looking for GOLY GL21 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my GOLY GL21. 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.

@Lori

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 GOLY GL21 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/are-stalion-cases-any-good-great-reviews-but-never-heard-of-them.3228497/
Take a look at comment #680
Also, this : https://xdaforums.com/t/anyone-wants-mod-edit.2343183/.
You can also check this video starting from minute 6:

The GOLY GL21 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 GOLY GL21 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 GOLY GL21 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 GOLY GL21 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/Answers/View/572816/Stuck+in+Account+verification+after+account+reset!

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

The entire flex cable containing the switch usually needs to be replaced. They are more energy-efficient for short bursts but can be more complex to drive. Power off the phone and remove external screws (e.g., Pentalobe for iPhones). Once it makes contact with the adhesive, apply gentle, even pressure around the entire perimeter to ensure the new adhesive bonds properly and creates a tight seal. Diagnosing issues with these circuits is crucial for addressing common problems like no charging, slow charging, or excessive heat during charging, requiring a deep understanding of power management and systematic troubleshooting. Doesn't Power On At All (Dead): No response to the power button, no charging indication, no sounds, no vibrations. Charge Battery: Ensure your phone is fully charged before flashing firmware or performing system updates. If damaged, it leaves the microphone exposed to environmental hazards, potentially leading to permanent microphone failure. This is the most definitive way to confirm seal integrity without water. If the phone gets excessively hot only when charging, it's a strong indicator of a charge controller or charging circuit fault. Safe Mode (Android): Boot your phone into Safe Mode (disables third-party apps). Rear Camera(s): Often the mic is near the rear camera, which might need to be disconnected and removed. Recovering a bricked smartphone can be a daunting experience, transforming your once functional device into an unresponsive paperweight. The principle is simple: light travels at a known speed, so by measuring the "time of flight," the sensor can accurately determine the distance to various points in a scene, creating a detailed 3D depth map. Keep track of all screws, noting their original positions, as they can vary in size and length. Examine Display Panel: Look for any subtle signs of internal damage on the OLED panel itself, discoloration, faint lines, pressure marks that aren't immediately obvious. Connect and secure: Reconnect any flex cables or ensure the spring contacts make proper connection. Observation: Monitor the transfer speed reported by your computer's file explorer. In this scenario, you're out the cost of the replacement screen, the tools, and potentially forced to buy a new phone anyway. Always ensure your smartphone is completely powered down before beginning any physical repair. Manufacturing Defect: Less common, but sometimes a motor can fail prematurely. Among the most frustrating and often complex issues encountered are software locks and activation errors that manifest after a successful physical repair. Cause: Flashing an incompatible or corrupt custom kernel, or making highly unstable changes to kernel settings that prevent the OS from loading. Update failures can stem from a variety of causes, ranging from simple user errors to more complex system file corruption or even hardware issues. Android: Settings > System > Reset options > Erase all data (factory reset). Gently apply heat to the area directly around the damaged camera lens ring using a heat gun on a low setting or an iOpener. If the microphone works in Safe Mode, a recently installed or misbehaving app is causing the conflict. You might find usage statistics, estimated remaining life, and sometimes temperature, but usually not a direct health percentage. Adhesive Strips: If your phone's back cover or screen relies on adhesive for reassembly and water resistance. Safe Mode Boot: Boot your phone into safe mode (search online for your specific model's instructions).

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