I assume you still have the manual unlock lock turn knob at the inside back of the door opposite end to the handle if so when you turn it clockwise about an 8th of a turn the mechanism should unlock however if it dosent go round with a sharp click try pulling rattling the door handle as you apply force to the knob and the mechanism may spring into place if your lucky had several successfull openings like this.
Transit side door wont lock.
Sometimes when you press the unlock button on the keyfob to unlock the rear of the van only the back doors unlock.
In my case i could have probably unhooked the yellow.
Try opening the rear door driver side and operate the inside handle.
I had to take out the lock to repair and decided to show whats happening when rotary knob gets stuck.
Info and repair ideas.
How to get into a transit when the key will not work.
The side door stays locked.
When you then try to lock the van by pressing the lock button it relocks the rear doors and beeps the horn to say a door not closed.
Sliding door lock not opening.
Video about how you can open stuck sliding door on ford transit mk6 van.
Issues in ford cars door locks and central lock system.
Then lock it all up as normal.