Well, there's a wire that connects the interior door handle to the latch mechanism. It seems my wire finally snapped from fatigue and I couldn't open the door from the inside.
Went to a salvage yard and tore out one from a wrecked door, and got it for free!
Needless to say I'm fixed, also fixed a burnt out light for the door handle as well, so two birds with one stone.
It wasn't too hard, just a pain to do. But it should last for the rest of the time I have the Tour...