Continuous crashing of iPhone 5 after iOS 8.4 update.
iPhone info : iPhone 5, currently running iOS 8.4.
So I've updated my iPhone 5 to the newest iOS 8.4 and it started crashing again and again. Everytime I insert my passcode and unlock my phone it brings me to my home screen but after a few seconds a black screen comes up ( sometimes with grey lines) and my iPhone blacks out and it restarts. This process mentioned above only happens after I unlock my phone after the restarts. If I do not unlock my iPhone, it stays perfectly ok on the lockscreen but it totally defeats the purpose of owning a phone since I can't access it anymore.
I've tried restoring it from a backup, resetting it to factory settings but it couldn't work for me since I need to enter my passcode to restore/reset, but everytime I do so the phone dies and disconnects from iTunes.
I am desperate of help, please provide solutions if possible. Thanks.
iPhone 5, iOS 8.4