One of the two USB 2.0 ports on the front panel header appears to have died after I plugged in a USB stick. BIOS post doesn't seem to recognize anything is plugged into it anymore, so it's not a software issue. I've updated my BIOS from 1704 to 2203 afterwards which set factory defaults and that didn't help.
The USB stick itself works fine in other ports. I've also tried another USB header adapter and only one port was working on that one too.
First you need to figure out if it's the header or the port. Does your case's front IO have more than 2 front USB 2.0 ports. (they usually come in pairs, aka 2, 4...) If you have 4 and you know those 2 ports are working, temporarily change the cable from the header they're connected on (and working), to the one the faulty port is connected to. So disconnect the cable of the faulty port (you'll automatically temporarily disconnect a 2nd port too. headers support 2 ports at once), and connect that other cable on it.
Does the problematic port work now?
If yes: the port itself is fine, the boards header is not. > RMA the board if no: the port is likely defective and the header is fine. > replace the case io panel
The Maximus X Code only has one USB 2.0 header. I did connect an older case's front IO USB cable to the header and one port on that one was dead too. So it's most likely the motherboard's header that has a dead port.
The warranty on the board expires at the end of 2022. Don't think it's worth sending it back for a single USB 2.0 port. There's no telling how long RMA will take nor whether I'll get a stable board back. I depend on this computer for work.
I'm somewhat surprised it just stopped working. USB ports tend to be robust in my experience.
I had to to an RMA of my VIII Formula due to a faulty USB 3 header too (by the time it arrived, don't ask me how. CPU socket was skewed too). Sent me a new one. Turnaround time. A week and the new board was ready to install.