MacMini M1 and Big Sur 11.6 firmware version

Apple menu -> About this Mac -> System Report -> Hardware Overview:

Hardware Overview:

  Model Name:	            Mac mini
  Model Identifier:	        Macmini9,1
  Chip:	                    Apple M1
  Total Number of Cores:	8 (4 performance and 4 efficiency)
  Memory:	                16 GB
  System Firmware Version:	6723.140.2
  OS Loader Version:	    6723.140.2

If you bricked your M1 Mac mini you will need another Mac, a Thunderbolt data cable, and Apple Configurator 2 installed on the other Mac to revive / refresh the operating system. Or you can bring it to a service center to do it for you.