some days ago my phone turned off unexpectedly and I found that it wont turn on until I connect it via usb to my PC!
other problem is with SIM card (may related to main problem):
operators network do not recongnized and device will turns off after some mintues if SIM is placed in device even I connected the usb cable.
after this problem I wiped all data and installed CyanogenMod 10.2.
my previous ROM was: CyanogenMod 10.1
Device model: LG-Prada P940
I just wana turn on my phone !