[Optimus L3, L5, L7 Q&A, Help & Troubleshooting] mkey82:
Hello all and thanks to anyone reading this. I'll try to keep it short.

My friend asked me to replace the broken touch screen on his Optimus phone. I ordered a third party replacement touch screen from ebay and whilst replacing it I managed to crack the LCD screen. Which, as it turns out, is quite sensible. So I ordered a replacement LCD screen from ebay (another third party product) and now this is what happens:

1. the device turns on nicely, vibrates, I get the LG logo and about 60 seconds later the device emanates some sound (supposedly welcoming the user to the "desktop") but then the screen goes (stays) black without the LG logo. I can see the background lighting and the two keys have their background lighting on, but that's about it.

2. while connected to the PC, the device is recognized as a P700 phone, can't access files though. I presume due to being unable to switch the USB mode. From time to time, while left connected, the device will vibrate with no visible change on any of the background lighting.

3. things I have tried:

a) starting the phone in "recovery" by having the volume up key pressed up while plugging the USB cable. Tried this both with and without the battery. No discernible changes occurred. I assume this would work only when a recovery image is installed, which this phone doesn't have.

b) tried to perform a "hard reset" by holding the power and volume down key at the same time and then tapping the menu key when the phone vibrated and soon thereafter releasing the power and volume down key. No change.

4. things I presume/ask:

a) the LCD screen is obviously working OK, since the LG logo is shown. However, there may be a possibility that a "lower" video mode is used during bootup which works, but when the phone tries to go to "full" mode and it fails. Don't know how these things work on mobiles, really. Seen similar stuff happen on PCs so I'm not really certain the screen is fully functional, compatible etc.

b) the touch screen, I have no idea at this point whether it's working correctly or not, is it compatible etc. Could an incompatible screen/touch cause something like this?

c) if I assume the screen and touch are OK, then it must be a software problem. However, is there an option to have this device flashed with a stock ROM without having the option to turn on USB debugging?

Currently, I have no idea which firmware version the phone is using. To the best of my knowledge, the phone isn't rooted since the previous owner had it just for a while and when the touch screen broke he handed it over to my friend and that's how this mess started. Honestly, if someone payed me to do this (which I wouldn't even accept due to being inept at such matters) I'd just reimburse them, scrap the phone and take this thorn out of my posterior. However, with people you know and have decent relations with it's hard to settle such matters so I'd really like to repair this little phone.

Previously I have managed to change roms on some of my phones (T-Mobile Pulse, xperia Ray; without actually bricking anything) so I have a general idea on how these things work, but this issue is well over my head and therefore any advice would/will be greeted with a giant gaping smile on my face.

To end with a fitting quote: "Favor gonna kill you faster than a bullet".