Phone won't stay on when unplugged from recharging

Left my phone on and on dashboard of car on a very hot day in full sun. Motor off but plugged into charger. When

retrieved it tried to activate screen it only recycled like it was trying to turn on.

It will turn on now if plugged into charger but as soon as I unplug it starts the recycle mode trying to turn on. I cannot shout it down have to remove battery. Is there a fix?