W210 - Boot lock & interior release light on

Have a 1999 E240. The boot won't lock on the remote (but other doors do, and the interior boot release has the red light on and doesn't seem to do anything.

I've checked the fueses and they seem ok

When locking the car on the remote I can't hear any noise from the boot lock (like i can on the doors and fuel flap etc)

Any advice would be helpful....