Guide on How to Fix ASUS Motherboards That Black Screen Brick on BIOS Update
I've had to deal with my ASUS Z390 motherboard bricking every single time I try to update the BIOS (the very first time was absolutely frightening for me), so I decided to share the instructions for posterity in case others ever experience bricking as well. (This is also to allow Google and whatnot to index it for people to find it easily.)
(This only works on BIOSes with on-board graphics, so if you don't have one, you're probably doomed if it bricks and will have to use the backup BIOS.)
If you're reading this ahead of time prior to a BIOS update, keep in mind to have a USB handy and to save your CMOS settings to it so that you don't have to redo everything afterwards. You can back it up from the Tools menu, by saving it to your USB with the F2 option, not the one that uses Ctrl.
Essentially, when you update your BIOS and it completes, a black screen brick happens if the BIOS restarts to complete the installation, but then the screen shows nothing and the PC simply hangs indefinitely, even though it's still running. If this is what you're experiencing, do this:
1. Force the PC off with the power button.
2. Turn off the PSU, and then pull out the power cord.
3. Detach all of your monitors (from the GPU) and attach one to your motherboard's video output port.
4. Wait another 30 seconds or so, and then reattach the power cord and power up the PC.
Once you do that, it should be back up and running again, but with the classic POST screen and the BIOS reset. You'll need to press F2 to get into the BIOS setup from here. Then just restore your BIOS settings and save and quit.
Anyway, that's it. I just wanted to share it. I'm surprised that ASUS hasn't fixed this, but I hope they do for future generations.