I'm having the same problem only worse.
I dropped my G3s 16 gig and the glass cracked in a hundred slivers but still worked just fine.
I ordered a new front glass panel that I replaced today but after reassembling the phone and turning it back on, I got so far as to enter my sim card number and open up to the front page but when I went to make a phone call, it went white screen and everything I've tried hasn't worked to get it back to operational.
I've tried the power and menu button thing as well as itunes reboot.
I'm wondering if the new glass and digitizer might not be compatible with the old lcd screen.
Should I have got the whole unit as one instead of just the glass/digitizer assembly?