iPad 2 iOS 8.4 looping on apple logo and cant charge fully.

My iPad 2 now on iOS 8.4 is stuck on a continous 'apple logo to home screen rebooting loop' and when plugged in to charge displays a different battery % from what it showed before. My problem started after i JB'd on iOS 7 and since then i got it to work after pressing the Home and sleep/power button for 40-100x whenever i saw the apple logo. it then was able to charge while switched on(not off). I recently upgraded to iOS 8.4 and tried to back up but cant as it disconnects while syncing before i get to be able to backup. pls help.