This iPhone 4S was brought to us after it had a screen replacement carried out by a local company that advertises iPhone repairs, When the customer brought it to us they said it had worked fine part from broken screen (which had been broken for months) when they got it back with the new screen they then complained of a signal issue and the battery was draining very quickly, when i heard this i suspected board damage right away caused by technician that had been repairing the handset,  Below is a picture of the area that was damaged from a fully working phone, so this will give you an idea of what its suppose to look like

iPhone 4s no signal after screen changed

Now that you have seen what its suppose to look like now i will post a pic of the damaged board, with the repairs carried out to it so it will work again. you will see there is a large capacitor missing which was caused by the person who fitted the screen and also 2 small blue filters missing meaning the phone will never get signal with out these filters,

You will notice the 2 blue filters are missing and have been bridged to return the signal to the iPhone, also you will see there is a large cap missing, below the right hand pad of the cap you see another cap missing, this cap was removed by iPhone Bits as it was causing a short meaning the battery discharged very quickly, the caps can be left of as there are merely filtering stuff which does not make a noticeably difference to me or you (the end user)

If you have any questions about iPhone 4S No Signal after screen change  replacement then please contact us as we may be able to help

Thanks to Janine for giving us the chance to show people how to repair an iPhone 4S with signal issues After failed screen replacement