Build won't boot to bios after bios update. Motherboard Error A2.

[fs61]

I've finished building my first pc build. At first it booted up to the BIOS and I hadn't touched it for 4 days since I didn't have time to actually work on. I finally did and the first thing I did was update the BIOS by downloading the appropriate update from the Asus website. 

It all seemed to work out fine but it hasn't restarted since the screen went black. The mother board has the A2 code on it along with a white light. It's been like this for an hour already. 

The update is on a flash drive plugged into the BIOS labeled port on the motherboard. After the update started I unplugged other USB connections. I also switched out the HDMI cable from the GPU to the motherboard and tried a different cable. Nothing popped up after the cable changes.

I've been scared to restart it with the restart button since I've read this can really mess up everything. I genuinely don't know where to go from here since the solutions that I've found all need the BIOS window to show up. Any help or advice would be much appreciated. 

The specs are below.  

Intel Core i9-14900K 3.2 GHz 24-Core Processor

Noctua NH-U12A chromax.black 60.09 CFM CPU Cooler ( have 7 fans in the case)

Asus ROG MAXIMUS Z790 Dark Hero Atx LGA1700 Motherboard

G.Skill Trident Z5 RGB 64 GB ( 2 x 32 GB) DDR5-6400 CL32 Memory

Samsung 990 Pro 4 TB M.2-2280 PCIe 4.0 X4 NVME Solid State Drive

Asus ROG STRIX Gaming OC GeForce RTX 4090 24 GB Video Card

Seasonic Prime ATX3.0 PX-1600, 1600W 80+ Platinum, Full Modular, Fan Control in Fanless, Silent, and Cooling Mode, SSR-1600PD2. 

[JohnAb · Accepted solution]

Did you unplug the other USB connections while it was doing the BIOS update? If it is stuck after an hour, then it's not going to recover on its own. 

I think your only option will be to power off, restart and see if you can get into the BIOS. If not, try flashing the BIOS again. 

[fs61]

I unplugged the other usb devices after the progress bar had filled and the screen had gone black. It was down for 10 minutes and I started searching the A2 code. Found something about it not being able to find it's way to a boot device. So I unplugged after that.

[fs61]

I guess it worked. I just pushed the power button and it turned back on fine so far. Seems to have also updated the BIOS version. Thanks for the reply and advice. 

[dennys2009]

Hi!

1. Disconnect all sata cables from the motherboard
if connected and disconnect everything from USB ports.
2. Resets Bios settings.
3. Roll back to the original Bios version.
If nothing helps, most likely not the serviceability of the hub (Z790 chip), there is only a warranty replacement.