E39 | Key won't turn the driver door lock, everything works otherwise

2001 525i sedan. The only surviving key is some cheap aftermarket fob of the switchblade style.

The central locking mechanism is overall fine. I can un/lock the car with the remote without issues. I can put the key in and start the car without issues. The key can physically un/lock the trunk without issues, but the driver door lock just won't turn more than like half a degree in any direction. It's quite stuck. I've tried lubing up the key with wd-40 and then graphite, did not work. I've tried unseizing the lock with wd-40, did not work. What are my options here?

Repeat just to be clear: the driver door's locking mechanism works fine with the remote, the central lock button on the center console, and the little lock pin. It's just that you can't physically operate the lock with the key. I can get in and out of the car just fine as long as the car's got power.

inb4: I know wd-40 is no lube. I'm just trying to get the mechanism to move again.