Sorry to hear this
A couple of questions.
1. Was it the other party's fault, and if so has their insurer accepted liability? Have you made a claim directly against the other party's policy, or are you claiming against your own policy? Did the insurer provide you with a rental car while your car is being assessed? Has the car been taken to a Mercedes Benz dealership, or to a repair facility chosen by the insurer?
2. Do you have any finance on the car?
Regarding the damage to the car, these days insurers are very quick to write off damaged cars. Even more so if the repair is to be done by an MB dealer. If the insurer does not approve a repair, then they still get some cash from Copart who will auction the car for parts, and they avoid the potential pitfall of additional damage being discovered while the work is ongoing. Plus, they don't have to pay for your rental car for the duration. For this reason, even a relatively small damage can write off a car these days. Obviously, being an EV, the question mark around possible damage to the battery makes it even more likely that the car will be written off.