Well my friend came to me with a LG smart phone after flashing a custom rom on it and it never boots … It kept displaying udc_start() on boot, which meant it was booting into fastboot mode. I tried restoring via the volume down and power button, no luck. Also tried fastboot commands over USB cable to flash a recovery with the ” fastboot flash recovery” command in command prompt (no luck). I tried going into recovery mode, no luck as well. After fiddling around the internet, I found a way to restore almost any soft bricked LG smart phone back to factory condition. Most of these bricks result in the phone being stuck on the LG logo boot loop or booting into fastboot mode (UDC_START()) .
Follow the steps below to try to unbrick your LG phone
I take no responsiblity for any issues you may cause and this may brick your phone further, but this did work for me. Proceed with caution and at your own risk
,also this will erase everything on your phone!
I used this method on a Windows 10 Pro 64 bit machine and it worked ok.
The LG support tool will not flash a phone with low battery, you need to charge your phone before you flash it
1. Download the LG Support tool from LG Here
2. Install this and open the program called LG support tool in your start menu after it installs
3. Click on install USB driver and select your phone (you will need the model number , pull your battery out and look at the label under it if you do not know what model your LG phone is).
4. After this is installed, plug in your phone via USB and boot it into download mode (most LGs boot into download mode with Volume up , Back key (next to home button) and the power key pressed down during booting, google how to do it on your phone if this doesn’t work) —- Be sure to hold the Back key as well – most of the info online says to only hold the power and volume up key … this was the problem I had and it never went to download mode .. the proper key sequence was power , volume up and back key
5. Once booted into download mode , in the LG support tool, it should detect the phone and say it is already updated
6. Goto the Options menu and click on upgrade recovery
7. Go through the prompts and this should flash the phone back to factory.
This should work for all the Android LG phones such as the G2,G4 F6, L90 etc. Let me know if this works for you. Surprised this isn’t on more message boards etc.