You can back up to iCloud and reset the phone. When getting it back, log in and wait 30min, everything should be there.
You can't diagnose hardware problems without access to the software and any limited "service mode" is just a backdoor in waiting.
You can back up to iCloud and reset the phone. When getting it back, log in and wait 30min, everything should be there.
You can't diagnose hardware problems without access to the software and any limited "service mode" is just a backdoor in waiting.