Bottom line here there is a
fuse or fuses somewhere.
If the unit is completely dead it’s almost certainly a
fuse which has blown.
Most chargers are independently fused.
The
fuse can be of different types from the bladed
fuse shown on Trevs post which tend to be external, (but can be internal) to a glass
fuse on the printed circuit board.
But your vehicles 12v system will be protected with a
fuse box, and the charger will definitely be protected from there.
Simply putting probes on the + and the - power terminals at the charger will let you know if the supply is reaching the charger. If there is no reading there, then it’s your vans
fuse which has blown, if not it will probably be a
fuse within the charger.
Find out the model and look for instructions and spec online, this could give you what you are looking for. It’s odds on there’s a supply issue, and if there is replacing the
solar controller won’t solve the issue if the supply problem is from the 12v supply in the van.