Does the *unlock* function work?
If so, be aware that MB has a system (at least the T1Ns have it) whereby the electronic locks get disabled if it *thinks* you're about to crash.
(this way the doors won't lock blocking rescue attempts)
Hitting a parking lot bollard or loading dock a bit too hard can set that state.
A dealer-level scanning tool can clear the status (but a generic OBD scanner cannot)
---dick