Mine needed rebooting a few times before it stayed on after a 100% charge and showed the plug it in graphic when I tried to turn it on. But when it stayed on the battery was fine for a few days so clearly not a battery issue. The fix is book an appointment with an Apple genius at an Apple store and say the recent update has screwed the battery firmware calibration. The appointment arrives by email suggesting back it up and make sure it’s up to date (but auto updates was on). So plugged it in for a really long update installation (so long I had to cancel my appointment) but surprise surprise problem fixed!![br]
Apple trying to sell more iPads again!