This issue has a number of potential possibilities for occurring. Most commonly the date and time on the phone are not current, due to new hardware being installed reverting the phone back to its original factory settings. If the time happens to not be current then simply change it and that should be enough to fix the issue.
If the problem does persist even after changing the time, it is best to then open up the device once again to reconnect the service antenna. If this does happened to be improperly connected then this is clearly the reason for the ‘searching’ fault. Please feel free to contact us though if the problem still persists.