It sounds like a remote code mismatch. If the display is "1 CHK REMOTE", then it's the remote which has changed rather than the recorder.
The remote code is set by holding either 1, 2, or 3 and pressing ENTER while holding down the number. It may be that this happened by accident.
To fix it, just see which number is displayed before the CHK REMOTE, hold down that number on the remote and press enter.