If you have an Intel Mac, then try an SMC Reset to force a power off of the laptop.
If you have a 2018+ Mac with a T2 security chip, then you can try to "Revive" the T2 firmware, but this requires access to another Mac running macOS 10.15+. This option helped another user when the Monterey upgrade failed on their 2018+ Mac with a T2 security chip. You can have Apple or an AASP perform this option for you (an AASP may charge for this service if out of warranty).
Revive or restore an Intel-based Mac with Apple Configurator 2 - Apple Support
Revive or restore a Mac with Apple silicon with Apple Configurator 2 - Apple Support
If your data is important, then you should always have frequent and regular backups. And you should always make sure to have a good backup before even attempting to upgrade macOS which is a very major change to the computer. FYI, it is impossible to recover accidentally deleted data from an SSD after the Trash has been emptied plus an SSD can fail at any time without any warning signs. With a USB-C Mac the SSD is integrated into the Logic Board making data recovery even more difficult especially with a 2018+ Mac with a T2 security chip where is absolutely requires a working Logic Board and T2 chip in order to access the data on the SSD. Plus as you have discovered the OS upgrade (even an update which updates the firmware) can cause the firmware on the Logic Board to become corrupt which requires replacing the Logic Board (if Apple performs the repair or replacing the firmware chip if a non-Apple shop performs board level repairs), or by "Reviving" or "Restoring" the T2 firmware on a 2018+ Mac. Apple includes Time Machine backup software with macOS so there is no excuse not to have a backup.
Edit: If you have a non-USB-C Mac, then you will have to have Apple or an Apple Authorized Service Provider (AASP) examine the laptop and provide you with a repair estimate.