If you check the forum you will find quite a lot of advice. It would appear that the PSE pump has failed. Check the 20A fuse behind the drivers seat (it is under a false floor) - around about the middle of the row - should be the only yellow one.
If it has blown, replace it but be prepared for digging!
If it is just the boot soft close not working, and the doors still lock OK, that'll probably be a vacuum leak in your boot lock. Mine did the same thing recently.
Basically you need to take the boot lock out out and epoxy all the little ball valves closed. There are six I think, I did that and no more leak. It will time out after a few seconds, but if you pull the fuse to re-set it, you should hear it hissing if it is leaking. There are many fixes on t'internet, I found a YouTube video and followed it. A new boot lock is £350 from MB, so well worth fixing yourself if you can.