Power button not working yet ipad boot loops when disconnected

So I have a bit of a weird one. The ipad came to me as broken because the power button wasnt working. Upon testing it I found the power button was indeed faulty however the volume up and down buttons are all working fine despite them being on the same flex cable. I decided to go and open the ipad up to check whether the cable was torn or damaged however when I go to turn it off it turns off but then boot loops. I hence thought ok it must be a dodgy power button but when I opened the ipad up and disconnected the entire flex cable the ipad is still bootlooping! It does this even when I disconnect and then reconnect the battery. The only way to get it to turn back on is by plugging it into power and then it will turn on allbeit without a power button connected. The touchscreen has also gone a bit dodgy but thats most likely to do with a poor quality touchscreen so I don't think this has anything to do with it. I would like to know is this alright behaviour for a faulty power button or is it a motherboard issue? Also the back camera doesn't work, thought this might be related but probably not.

Any help would be much appreciated thanks.