Wierdly, it will shift channel If I take the headphone jack half out.

I know that makes it sound like the problem is with the headphone jack or adapter, but that is solid - and wouldn’t explain the weird cutting in/out when I press a key on the keyboard.

I’ll give a few more tires, and then follow your advise - backup and hard reset.

Fingers crossed… looks like no one else has had this issue. Lucky me!