They often seize up give the rod a bit of a twist and then close the boot.
Slk roof switch not working.
Next check the micro switch where the divider locks.
If the relay and the fuse are not the problems move to the next step.
If not the switch or wiring between the switch and relay could be the problem.
Roof will not open after dead battery.
There s loads it could be but make sure you have the blind pulled out in the boot and have a look at the rod that goes from the boot push key hole down to the latch.
Relays are affordable and having a spare is a good idea.
Swap it with a known working relay that is identical.
When putting switch in close position answered by a verified mercedes mechanic.
Slow blinking red light.
You can also bridge the top relay for a couple of seconds to see if the hydraulic pump start to run.
The relay can not be inspected visually but there are ways to test them.
Check the convertible top relay as well.