There is nothing wrong with your trezor, just use it, there is no need for you to invent the wheel all over again.
I agree. The outside cover being open does not compromise the device. It should be good to go, I'd keep it and save myself from all the trouble.
Great customer service though. Trezor gained a point here.
But why? reading the whole thread, everyone took for granted that this mere possibility would be a sure thing, and nobody encouraged the OP to try again. To be able doesn't mean they would.
If the device is sealed and there are no signs of the cover being opened, it's safe to use. Hardware wallets cannot be accessed remotely and you can't plant any malware that way. If there's no signs that it was physically tampered with (the device not the package) it's good to go.
I always refuse to accept damaged packages. I don't care if it was customs or someone else. Couriers have protocols for such cases. They write that the package is open and you sign that and it gets returned to sender.