I tried and succeeded in getting it to reboot again today;

After 10 minutes of listening to radio and occasionally hopping between preset stations I started to search for new ones. A few minutes later I decided to see if I could make it reboot like it had yesterday. While it was briefly searching in one direction I pressed the opposite button to search back the other way, after about 10 attempts the buttons became unresponsive and it rebooted ~15 seconds later. I think the off station background noise was present right up until the reboot started if that's relevant.

I spent the remaining 15 minutes pressing buttons trying to reproduce it a second time without success.

Reminds me of that joke:
Patient: "Doctor, it hurts when I do this" (Patient pokes himself in the eye)
Doctor: "Then stop doing that!"