In this video member GadgetUK164 cleans up the remote of his CD-i 210, give it a cap (which was missing), and he adds a CR2032 battery and hack away at the timekeeper chip. It's a useful and detailed video for all of us who want to do the same trick to their CD-i player to keep it alive!
If you have a CD-i player that does not load CD-i discs anymore, by giving an error message or simply doesn't show the "Play CD-i" button anymore, there's a chance your timekeeper battery is dead.
[Thanks, GadgetUK164]