iPhone 6 stuck and wont accept my passcode

It all started one morning my battery was low so i charged it and when it started up it wouldnt accept my passcode. I also realized that it wouldnt charge, it was just stuck on 1%. I eventually held down on the lock and home buttons to restart it and it started to work again, later that day the same problem ocurred. My iphone six wouldnt accept my passcodebut it shows my notifs. Also a message came on the screen saying the temperature of the phone was too hot and needed to cool down i left it for a while and the message went away.I tried to plug it into my laptop to reset the phone ir update software or something.. and the apple logo comes up for a few seconds, then it turns off and then repeats. after a day i left it on charge and the battery is at 100% now, but the phone only stays on while plugged in. i cant make or receive calls either. help please