This happened on a 10 plate transit last year more than once.
Transit van side door wont lock.
In my case i could have probably unhooked the yellow.
If your drivers side door won t open try spraying some wd 40 into the area where the door connects with the lock inside the car.
Video about how you can open stuck sliding door on ford transit mk6 van.
All motors work on all doors as can hear them even clear the contact on the side sliding door still does the same locks then unlocks its self deker gough may 2020.
Ford transit lwb 55plate lock with remote then it unlocks its self.
Try opening the rear door driver side and operate the inside handle.
Then lock it all up as normal.
If not if its the same then there is usually a sticking sometimes faulty lock mechanism on the van.
I had to take out the lock to repair and decided to show whats happening when rotary knob gets stuck.