Hi, I have a similar problem, well my g300 dropped from my bag, it seems that the screen cracked (but it is not visible). When I press the on button it starts with the logo and some big lines appear in the screen, then can see the locked screen for a while but as time passes the screen starts to flicker and little by little it became black (until I leave it for a couple of days in its case, then if I switch it on the process starts again) I have to add that can`t move anything with my fingers, I can just see the screen, no movements.
I know that the phone works, I think the problem is in the lcd display but I am not sure if the digitizer screen is also damaged. What do you think???
To change a lcd now is quite expensive £40 (more or less), but it increases £20 with the digitizer.
This is a photo i took before the screen becomecompletely black.
Thank you !!!