Has the car been declared totaled? If you can pull the back seat manual cable under the seat, you can open the back door and flip down the seat, but without any power, you won't be able to open any doors unless you break the window and reach in which can be very messy. Perhaps charging the 16v for a day or hours can give enough juice to open the trunk. This is the downside of everything electronic in Tesla, the emergency guide listed all methods to open the door from the inside without power but no mention of the other way, in an odd case like this can be challenging.