Hi
This is the second time i have replaced my iphone screen. The first time i replaced it no problems worked straight away. I had an older firmware aswell.
The second time I had the exact same problems as everyone here... Just kept saying SEARCHING up on the top left of the screen, It didn't know if the sim card was in the phone or out. I took it all apart again and looked at every connection and they were all perfect.
I tried the date and time thing because i was desperate, and no surprise it didnt work either.
'''I updated to the latest firmware 6.0.1 (10a523) and the phone started and worked straight away.
'''
Hope this helps
Liam