Vivaro with no ignition lights battery reads 12 v all engine fuse

If you can hear the central locking mechanism in that door, then a linkage inside must have come adrift. You would have to remove the panel and look. It appears to be a known issue!!

[Vivaro] - Side sliding doors won't open

https://www.vauxhallownersnetwork.co.uk > threads > s...
Jan 20, 2018 - Hi, My Driver door, passenger door and rear doors all open but ... in and out of the van today opening and closing the side doors so why ...

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  [Vivaro] - Slide door not opening

  https://www.vauxhallownersnetwork.co.uk > threads > s...
  Dec 9, 2013 - On the inside of the outer door handle there is a plastic link that holds the cable in place. When its all working, the handle actually pulls on ...
  
  

I have seen this and in most cases the problem is the master switch in the drivers door.

Rear fuse box. INT LP 10 amp . there is also INT LP relay in the same rear fuse box .
Fuse Block - Rear
Under the rear seat, on the left side of the floor pan
The INT LP fuse in the fuse block - rear supplies battery positive voltage to the normally open switch contacts of the INT LP relay. The INT LP fuse also supplies battery positive voltage to the INT LP relay control circuit. The fuse block - rear also supplies battery positive voltage to the relay control circuit for the front courtesy lamp. The door modules communicate on a simple bus interface (SBI). When you open any door, the switch contacts of the door open switch close. When a door open signal circuit is grounded, that door module sends a message to the drivers door module (DDM) in order to indicate that a door is open. The DDM sends a class 2 message to the rear integration module (RIM) in order to indicate which door is open. The RIM activates the INT LP relay in order to provide battery positive voltage to the interior courtesy lamps. When any front door is opened, the RIM will energize the FRT CTSY lamp relay grounding the I/Pcourtsey lamps at G302. Depending on which doors are opened, front or rear, the proper interior courtesy lamps illuminate. The RIM provides a pulse width modulated ground to all interior courtesy lamps for the interior lights theater dimming feature. Some of the courtesy lamps are also used as reading lamps, each reading lamp may be manually turned on or off using it's own respective switch

The 2.7 had alot of problems with the cam sensor. I would start there. Its located on the front top of the timing cover. Unplug it and see if it "Pops" attempts to start.

Start by checking your battery cables for a good clean contact at both ends. Also check main fuses.

sounds like a ignition switch on the steering column

I would recommend going to a dealership. Though more expensive, they are far more reputable than some guy that like chicken wing & pizza on his 9th 15 min break haha. Dealerships always go about the right diagnosis and approach to each issue, 1) the Car 2) the customer 3) everyone being happy in the end. Good Luck :)

does it try to turn over if not it could be that the battery is dead if that not it then you mit have a blown fuse

im thinking its the starter..i would take it out and brin it into like an autozone they test them for free..