I had a chance to buy 15 units of G3, all broken or faulty. The purchase was made via an Swiss operator who was about to recycle the devices, but instead of recycling I bought them via some program for that. They dont pay for recycling, I get the devices extremely cheap, no one pays any tax (Switzerland stuff and their laws)
First of all I want to say - LG made a phenomenal job of envisioning a device - G3 was superb compared to all the phones released in that time period (S5, OPO1, Z2/Z3, etc) with it's bleeding edge technology and phenomenal design (which I am sure inspired others to go bezel-less and edgy and so on). 2K screen, great chipset, infrared focus and insane camera quality, etc.
Only thing they made bad was actual hardware assembly: I have never seen such bad work in modern electronics judging just by the amount of extra-flux you can see on the motherboards, looks extremely sloppy. That kind of assembly eventually led to 1000 problems, which I am sure all of us G3 owners experienced past the 24 month warranty period. Some would go so far to say that this stuff with G3 could be considered Planned obsolescence with all the problems appearing just around the 24 months clock, and with the MM update (taking into account that LG held the Nexus flag at that moment and they went over their heads thinking they are going to surpass Samsung, just like Samsung did to HTC)
My 15 units were:
- 6 units BSOD
- 5 units screen flicker
- 2 units "wifi turning on"
- 2 units sim card removed and restart/No sim card/invalid card
Note: I am not electrician and I dont understand how to read schematics, all of my info came from people that I figured best know how to repair mobile phone stuff (and also speak THE WORST english)
G3 motherboard layout for future reference:
1. BSOD -
The problem is with bad BGA solder of MMC chip. Not the actual chip (very rare occurrence). In short: BGA Solder is type of assembly that uses little balls of solder instead of pins, to hold the chip in place. There are more than 60+ balls on the MMC chip so no homemade replacement is possible (there is actually a turkish video which is NOT the way to do it as the guy doesnt add new balls, just strips old ones away)
permanent solution: give it into a repair shop to replace or do a proper reball of the Sandisk memory chip
semi-permanent solution (sometimes works 100%): give the chip a heat of 120-150 celsius (no american units, sorry) for 2 minutes (using a high powered hair dryer of at least 2000W, or a proper heat-gun) with slight push (I used wooden objects so that Metalic ones wouldnt damage the chip) > this repaired total of 5 BSOD phones, just one went dead completely after several tries. ALL of my 5 units never went back to BSOD. Please, DO NOT use ovens or anything like that, If you dont have a god-damn hair dryer give it to a technician and ask him to blow it for a minute or so. Ovens WILL burn other parts of the board, and knowing how shi*ty the whole assembly is, baking the board will just detach other chips. If you apply pressure to the chip, use something wooden like a chopstick or a pencil (dont use bamboo, it will release oils, use dry wood)
2. screen flicker -
The problem IS NOT a graphic chip (analogix), the problem is NOT CPU, as many have speculated in the past and the people who putt thermal paste over a CPU need serious education on the topic. Thermal paste is in no way a magical substance that lowers temperature when applied - it's purpose is to fill the gaps between a heating body (CPU) and heat dispenser (cooling unit, cooler, aluminum grill, etc), so thermal paste is a gap filler, not a cooling magical stuff. With that out of the picture, the problem of the screen flicker is a completely separate integrated circuit which goes haywire due to some magnetic stuff:
PERMANENT SOLUTION (homemade doable):
Now first, go back to motherboard image, and on the front side of the board find Gyro Sensor chip - just above that chip, there is a grid of 5x5 pin-like circuits.
Now that you have located them, that is your LCD screen flicker solution: I didnt quite understand what is really going on there, but you need to apply heat (just like in the BSOD solution, same time same temperature), and use metallic object to "clean" the pins. He explained to me that the screen flicker is due to some magnetic residue that builds up in that circuits, and a clean metal will remove it. (how that is even possible I dont know but the solution works) Long story short - I used a really fine metallic brush (Dremel set) and once I heated it up, just strolled with brush over those pin-heads. According to the guy, the metallic object needed for cleaning should be non-magnetic. If you dont remove the screen flicker at first, use a really fine object to give all the pins a push (once heated), I used broken needle (regular needle is too sharp) or smallest Phillips screwdriver in my set. IMPORTANT: when doing this, there is a ton of chips nearby so it's smart to protect rest of the board with Alu-foil
total of my 5 screen flicker units NEVER went back to screen flicker issue. Special note: 2 of my units after completely removed screen flicker issue, immediately went to "no sim card" issue and I dont know how that is connected, but there is also a method for sim-card issue repair further down the topic
3. Wifi turning on/wifi grayed out/wifi scanning
The problem over here is also not the problem of the actual Wifi chip (motherboard image back side, red mark). The problem is the power controller located on the front side (red mark). It is also a BGA solder issue so it's repairable
permanent solution: reball or replace chip in proper mobile service shop
semi-permanent solluton: Use the same method of repairing as for the BSOD problem, but with applying heat + pressure onto the power controller chip. Be careful as there are tons of IC's nearby. Homemade solution worked partially for me - one unit (out of 2) is completely repaired, other unit actually went dead (I believe I gave it too much pressure, that was my first repair )
4. Sim card removed and restart/No sim card/invalid card -
The problem with this is also not a problem of RF chip (backside green) or the 2g/3g/4g chip (backside light red), and it is NOT a problem of Sim card slot: it's one lousy mo-fo chip that's not even listed in the hardware parts image, and it's only noted in the actual schematics (I believe it's a chip for regulating power onto the sim card slot and transferring data further)
this one (red arrow pointing onto it):
permanent solution: replace, reball or reflow in service shops (when I say replace, it makes sense as new chips out of the box have BGA balls already on it, just need to place it and heat it up)
semi-permanent solution: same method goes like BSOD and wifi problems - apply heat and moderate pressure with wooden object. The problem with this one is that it will reappear as a problem. I had one unit in the service shop where the repair guy gave it some insane heat for 5-6 seconds while protecting rest of the board, and it was permanent, no sim problem any more. In homemade variant, the problem seems almost unable to fix, but you need to be persistent. sometimes it takes 4-5 tries for the phone (placing the board, and removing it again and so on is a pain in the arse) to recognize sim and after that you are good for a month or so, once it "catches" I gave it a try with a higher temperature / less time (200c, 30 seconds) and it shows better results, I dont need to try the board for 3-4-5 times until it recognizes the SIM, it's imediately good to go, but even with that it reappears after a month, 2 months, but sometimes after only couple of days
one unit is permanent (reflow in service shop), others (repaired screen flickers that went "no sim card" ) bug me still with reappearing SIM problem.
There you go, I wanted to share this with everyone so you people wouldnt lose your mind with paper tricks, ovens, and such, as G3 is still really powerful device and it would be bad for all the units to end up in a bin. I am using 3/32 version with fulmics and it works as any new 600 usd device, if G3 still works without a flaw there is really no need to go newer, not yet.
END NOTE: every attempt at trying this is on your own responsibility, I am not responsible if you fry your board, break your device, or tear your flex cables and such.
END NOTE2: in my experience, dont attempt to try the newly repaired board with battery less than 40%, I wont get into it right now but all Li-ion/Li-poly devices work at their best when there is a good charge
good luck with potential experiments fellow XDA people