Got a water damaged iphone with cracked front lcd screen and rear camera out of action. I replaced lcd/digitizer, battery and rear camera. Cleaned inside with alcohol. After putting back the iphone 4S, I got "searching" and then "no signal" Tried manually setting time then back to set time automatically, turn off then on phone, airplane mode , removed then reinserted sim card , on then off etc etc. and combinations of above. Then restored to factory settings and restored to previous backup. Now working!!! always backup to itunes before doing any work replacing parts.