[SOLVED] I'm looking for GUANAIXIN G1 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my GUANAIXIN G1. 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.

@Abigail

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 GUANAIXIN G1 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/Guide/Kyocera+Echo+Front+Screen+Replacement/117001
Take a look at comment #965
Also, this : https://xdaforums.com/t/does-nubia-has-the-pc-suite.3635513/.
You can also check this video starting from minute 2:

The GUANAIXIN G1 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 GUANAIXIN G1 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 GUANAIXIN G1 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 GUANAIXIN G1 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/465731/Screen+is+not+working+on+HP+Chromebook+11

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

This repair is best for high-value devices or when the component cost saving is substantial. Once loosened, gently open the screen like a book (direction varies by phone), being mindful of the display and digitizer flex cables connecting it to the motherboard. This information is then sent to the phone's operating system, which adjusts the screen's backlight level accordingly. Test in Safe Mode (Android): Boot into Safe Mode (refer to Topic 2 for instructions). Display Gaps/Loose Components: If your phone's display has lifted even slightly, or if internal components (like speakers) are loose or improperly seated, sound from the earpiece or external speaker can bleed through these gaps and be picked up by the internal microphone(s), creating an echo. The challenge here is to remove the old foam without damaging the delicate microphone beneath it. This is a fundamental safety step to prevent electrical shorts and damage during the repair process. Check main power rails on PCB for short to ground using continuity/resistance. Is it bent, warped, or crushed? Any external deformation can hint at internal pin issues. If, after meticulously going through all these diagnostic steps, face unlock continues to fail, especially after a factory reset and with clean, unobstructed sensors, then a hardware malfunction is the most likely culprit. If the sensor is confirmed faulty through the flashlight test during a call or persistent auto-brightness issues after cleaning and software checks, hardware intervention is necessary. Standard Smartphone Repair Toolkit: Pentalobe (for iPhones), Phillips, Tri-wing screwdrivers, spudgers (plastic and metal), heat gun/pad (for adhesive), suction cup, fine-tip tweezers. Align the coaxial cable connector perfectly over the receptacle on the motherboard. Proximity sensor or ambient light sensor flex tears would lead to those specific features failing. Patience and precision are your greatest assets in this demanding repair.The logic board, often referred to as the motherboard, is the central nervous system of any smartphone. Pulling flex cables at an angle, forcing them, or prying components too aggressively can bend or break connector pins. Cut Wire: Cut a piece of enamel-coated jumper wire slightly longer than needed for the bridge. A thermal camera (or even careful manual touch) can identify hotspots on the device. Carefully prop the screen open at an angle using a suitable object or, if available, have a second person hold it for you. Screen replacement on smartphones with extreme curves is an advanced repair. Software Calibration: Sometimes, sensors require system-level calibration, but usually, this happens automatically. Gently slide the new SIM tray, with the cards loaded, back into the slot on your phone. Outdated firmware can cause various network issues, including authentication problems. High-Quality, No-Clean (Liquid or Gel): Essential for proper solder wetting and flow. Position it centrally, at a comfortable height for prolonged viewing, with sufficient clearance for your hands to work underneath. If a screw is stuck, a drop of penetrating oil (like WD-40, sparingly applied with a toothpick, then wiped clean) or a rubber band over the screw head might help. Lifted Pads: The copper pad separates from the PCB substrate but might still be partially attached. SIM Card: Test with a known good SIM card, and test your SIM card in another phone. Troubleshooting errors related to the digital crown or side key requires a systematic approach, moving from simple software checks to detailed hardware inspection and replacement. Reconnect Peripherals: Reconnect any other flex cables that connect to the new module (e.g., loudspeaker flex, antenna wires).

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