If your ipod touch 3rd generation is still white after the power/home reset, try desoldering the battery and resoldering it back onto the motherboard. This helped for me, and helps especially when either your power or home button doesn't work. After you've soldered the battery back onto the motherboard, plug in your device to your computer and you should get the apple boot logo right away, if your battery isn't dead. If you still have a white screen, either your lcd screen is bad and you need to get a new one, or you've snapped off a resistor that is necessary for your screen to light up properly. If your case is the latter, try steadying your hands in order to solder that resistor back onto the motherboard. It's a 50/50 shot. This has worked for me but only half of the time.