Tried searching but didn't seem like anyone had a similar problem.

When I try to do a bios flashback using a USB, I don't get any flashing lights. Instead, after 5 seconds, the system simply boots and gets stuck with a CPU debug light.

I know the rest of the components work because it posted once today. I know the USB works as well because I did a bios flashback on this exact setup with that usb. To explain, I just built a new system today using a 3600 with the carbon pro ac. I couldn't get the pc to post and the CPU debug light was always solid. Finally after doing bios flashback to v17, it posted. I ended up turned the rig off to relocate the build and then once everything was set, I tried turning my computer on but it stopped posting again. After hours of trying to get it to work again, I found a v18 bios on this subreddit which seems to work for many so I decided to give it a shot. But now the Mobo won't flash anymore. Instead of the red flashing lights that I got earlier, the USB would light up after 5 seconds and the PC would boot up with a CPU debug light. If I press the flashback button when the USB is in any other position, I'll get 3 flashes before a shut off.

Anyone have anything similar or know what to do?

Update: as weird as this might sound, I switched to a different PSU and the USB bios flashback seems to be working. Got it to post once, but no longer working again.