Input frozen following updates

I have an OSMC install we use on a PI3B when we go on vacation, so I only pull it out of the closet and update it every so often. It was on a December 2023 upgrade, and I plugged it in today and upgraded it. Following the upgrade, all USB input has been disabled, I tried 3 different USB devices in multiple ports. I can see the clock advancing on the home screen, and I can ssh into the box (apt shows up updates available on Debian Bullseye). Am I stuck? I don’t have kodi remote setup or anything, so I can’t seem to find a way to do any input at this point.

If you have ssh access, you can at least try to bring the device on latest greatest OS stand:

sudo apt update
sudo apt dist-upgrade -y
sudo sync
sudo reboot

What USB devices you’ve tried?

I tried that command sequence, no change. I used a logitech wired keyboard, a microsoft wireless KB, and a generic wired USB keyboard, no change.

Well, then I suggest you grab a new SD card and install OSMC onto it. If the device comes up without an issue booting from the new sd card, you know something very bad happend to the old sd card and software stack. If the device still shows issues, it’s likely the rbp 3B hardware.
Can you also try another power supply if available?