The new 12v batteries are lithium. If the fire starts in the 12v battery it would kill the electric door opener / windows. So this is the most likely cause.

Tesla still comes with analog flow handles for emergency situations like this (or if you drive your car into the ocean). Clearly stated in the manual or can be found if you search for 5 seconds.

Learn to know your vehicle before shit happens. 2020, there were around 173,000 highway vehicle fires reported in the United States. Learn how to get out of your vehicle when electrics are compromised.