Firmware update from more than an hour…
From Universal1.6.3 to Universal1.12.1. On the Trezor Installing… Please Wait.
If I turn it off, what happens?
Your seed gets erased and you’ll have to restore it from backup.
If you have the backup, nothing to worry about.
If you don’t, you’re SOL already. The updates don’t take that long, stuck for an hour almost certainly means that some packets got lost and Trezor is waiting for data that Suite thinks it already sent. At this point the situation might be recoverable if you keep the Trezor powered and connected and can guess the exact point where to resume. (in all likelihood it’s the start of the data, but it’s not a 100% thing)
A skilled specialist may be able to save you, in theory, if your savings are worth the expense.