iPhone 7 boot loop
So a family member gave me an iPhone 7 to repair and upon inspection the screen had popped out, this was due to the battery which had expanded. Turning on the phone it appeared to work but it was constantly booting to the app logo, then a few seconds later a black screen would appear followed by the Apple logo again. I`ve since tried 3 new batteries and also used different screens but still the issue remains. I`ve tried to update and restore via DFU mode but get the error 9 message in itunes while its attempting to verify the update with Apple. I`ve completely disassembled the phone and cleaned all the parts with IPA but the boot loop persists, has anyone got any ideas I`m completely stumped.