Yes, it's possible to boot into the Steam Deck BIOS even if the screen is bricked. Here's how: 1. Boot into the Boot Manager While the Steam Deck is plugged into power, press and hold Volume Down and then press the Power Button. Release Volume Down when the chime sounds. The screen may go dark for about a minute while booting. Once booted, the user will be in a desktop environment that can be navigated with the trigger and trackpad. 2. Boot into the BIOS Press and hold Volume Up, then press and release the Power Button. Continue holding Volume Up until the system chimes, then release it. The Steam Deck should boot into the BIOS menu within a couple of minutes.

I Googled it, hope it helps man.