4wd issues after MOT work

I hope you can help asap as I need to call the garage in the morning. I have a 2003 jimny and recently had the front king pins, bearings and seals replaced. Stupidly I didn't check 4wd when I left the garage and today, with 9 inches of snow, find the 4wd light flashing and no 4wd. There's no audible click on engaging and a slight hiss sound. This is too much of a coincidence to me considering the work the garage did and the fact it was working beforehand. What could they have done wrong? Thanks in advance!

My first thought would be the two vacuum lines where they go into the hub.. A very easy fix if they forgot to attach them..
The hiss could be the vacuum sucking !

Could have forgotten to connect the vacuum pipes back on the hub
Or pipe maybe split

Thanks guys. Me and the husband have just been fiddling and wondered if it might be something along those lines but couldn't trace the hiss. Sod's law says that they can't fit me in until after the snow's gone and we no longer need it, but if It's potentially an easy fix it sets my mind to rest a little. The work cost me over £800

Top of disc is 12 oclock, so look behind the disc at the hub around 10 oclock and there are two rubber pipes that push onto the hub.. these are what may not be connected or have not been pushed on properly,, no tools needed other than a torch to fix (if that is the problem)

Brilliant, thanks. We'll take a look first thing in the morning.