I just did a screen replacement on an Iphone 4S and have checked all connections they are all good, blue resistor is still there. Everything else works fine, WIFI signal is great etc.
Problem is that it doesn’t recognize if I remove or insert the SIM card and all I get at the top of the screen is Searching…
I searched 4 hours on this particular problem.
Soo here it is –>
When you replace a lcd screen on an iPhone 4S with iOS 6.X, make sure you change the time to current! (Auto -> manual)
The default time when replacing the battery is 01 : 01 1 jan 1970.
This problem is related to iOS 6!