Probably. It seems it was designed to run with the crypto after one month. Trezor's security on the physical realm is pretty good, but this is just a good attack.

How can a successful firmware update possibly be validated if you can't trust the device in the first place?

An attacker can just implement whatever "install firmware version xyz" command by returning "ok, did it!" and remembering that version number if it ever needs to be displayed.

A more complex attacker could emulate the entire firmware in more powerful hardware of the same physical profile and selectively intercept any input and output.