Worst case, the battery will drain eventually.
For the BlueTooth problem, this has worked for me. Take bad phone to one end of house or Apt, or leave the phone in the house and you head to store. Once the Bluetooth disconnects, pair with the other device. Normally, this will make the default to be paired with the new device. As long as you do not disconnect from the new paired device, I think you will be fine.
Update: The phone has finally run out of battery, and the affected area of the screen contiues to shrink.