Slightly off topic but this has intrigued me for ages, you state "B32 possibly feeding two radials" as that's what it looks like but I don't believe that device has any over current protection at all, its just an RCD with contacts rated to 32A just like the 63A and 80A RCD's we so often see in consumer units.So is RCD tripping?
Obviously cracked box, SWA not earthed this end, and B32 possibly feeding two radials (or is it a RFC?)
All I'd care about is understanding the reason why it doesn't work, and then whether the incoming SWA is sound. IR test it, continuity test it. I'd assume the other end is a fuse or MCB?
Then I wouldn't want to do anything other than start again. From what you've shown I've two instant ideas:
You could fit a little IP65 CU, re-terminate the SWA into that (but earth it), and fit a couple of B16 RCBO's, one for each shed.
Or you could re-terminate the incoming SWA into a galv besa box, or resin joint, extend the SWA and and fit a little garage CU inside the shed.
He could have some lights then as well.
The bit that intrigues me is why would manufacturers make an RCD that is only rated to 32A when they produce so many that are 63/80/100A rated. what could it possibly be used for that a vastly more common higher rated one couldn't be. All it does is confuse people into thinking its got some kind of over current protection, I'll bet there are hundreds of these devices installed for just that purpose.