Keyboard not working

Starting a new thread here since the old ones are getting pretty outdated.

I have a desktop setup that was working perfectly fine until I decided to clean my room. While moving things around, I bumped the desk and slid it back into place. When I went to power everything up, the keyboard wouldn't respond. I checked the back and realized the cable had been yanked out of the port because it got caught when I pulled the desk away.
So, I plugged it back in (it's a PS2 connection), restarted the computer, and... nothing. Total silence. I checked under the Device Manager, but there's nothing listed there. To make matters worse, the PC lost power, and since the CMOS battery on the motherboard is dead, I need to hit F1 to continue just to get into Windows. Now, I'm stuck in a loop where I can't even get into the BIOS. Every time I plug it in, the lights on the keyboard flicker for a split second and then die. Nothing works—even the Num Lock won't toggle.

I've inspected the pins, and they don't look bent.
The smartest move would probably be to test this keyboard on another machine or try a different keyboard on this one, but I don't have anyone nearby I can borrow gear from for a test like that.

It’s an old-school Microsoft keyboard, the standard kind. This is a 21st century problem, right? Any advice?
The PC itself is pretty mediocre; it's just a basic machine used for Microsoft Office tasks, so I'm not looking to sink a ton of money into it.

Maybe the battery on the motherboard just drained completely? Honestly, it might be worth grabbing a new one—it’s probably the cheapest little fix you can try to figure out if the PC will even turn on at all. Since you mentioned the computer lost power entirely, anything could be happening... for instance, there's always the possibility that the motherboard itself finally gave up the ghost.

It wasn't actually a power outage. I just flipped the switch on the power supply off and back on—a pretty stupid move, honestly, but you don't really think straight when you're losing your mind.
I’m convinced the PC just isn't recognizing the keyboard, which is why nothing is working. Like I mentioned earlier, everything was functioning perfectly fine once I was at the desktop, except for the keyboard.

It’s pretty likely that besides the cable getting yanked out of the Xbox at the flooded port, one of the internal wires snapped somewhere along the line.
So, I'm looking at a new keyboard and a fresh battery for the motherboard, which should run me less than $33 in total.
ps:
If the keyboard doesn't have a native Xbox plug but still won't work with the BIOS via USB, you could always try a USB keyboard paired with a little USB-to-Xbox adapter.