Iphone 6 restarting

Customer brings iphone 6 in recovery mode restored ios on it came back to life, i give customer iphone and he goes. He comes back later in the day that the iphone restarts randomly, then goes into a reboot loop. I try restoring but keeps giving error 9. Then i give to hardware department to check phone is okay buh dey removed the earpiece flex connector and i restored no error it works fine then an hour later it reboots but not randomly as before. Naw the iphone works an hour or 2 before rebooting with the earpiece connector not connected. With earpiece connector connected it reboots randomly.

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