If you do not get current to the starter lock, you will have to look in the car documentation where the fuses and relays boxes come, since it usually carries two, one inside the cabin and one in the front vain.
It would also be interesting to say if it is an ancient Vanette, or if it is a Vanette Cargo / Nissan Serena. Because there are things that change from one to the other.
Another thing you can do is get a fat battery positive cable and try to feed the Bombín terminal to see if you have contact and start.
If you respond, you have the failure between the starting hype and the positive cable that feeds it through its corresponding fuse. (Look a look at the connectors' chips as the companions say that sometimes they give a lot of war).
All the best.