Most likely something went wrong during the firmware update and your Trezor’s memory was wiped. This is a security feature and commonly caused by losing your connection during the update.
There is no need to worry, all you need to do now is run a recovery process using your recovery seed words. You can find a manual on how to recover your wallet by following this User manual: Recovery.
Once that is done you should be able to access your wallet with all your coins.
Please note that if you were using passphrase protection prior to the firmware update then you will need to re-enable it in the Advanced menu tab and then enter your passphrase to access your coins.
Without a copy of your recovery seed, unfortunately recovery may be impossible.
If this hasn’t helped, contact our customer support here: Customer support contact form.