My 2 back doors are locked and will not come unlocked.

You will have to remove inside door panel and manually release the latch to get the door open than flip the child lock in the door jam with door open

For this type of problem I recommend YouTube. Always a wealth of information on rear gates door locks etc.
Google > YouTube 2000 Ford Explorer door locks

This site shows you the detail of child safety lock:
Peugeot 308 Handbook Child Lock

Peugeot 308 Handbook Child Lock

child locks are on the back doors only and are underneath the door at the trim edge around seat height. If you cannot open the door from the inside but can from the outside then it has child locks.

Make sure child safety lock-out is not engaged for this door. There is a latch in the door and it prevents the door from being opened from the interior.

Sorry I do not know the configuration within the door frame. You may or may not need more working room. Some seat bases are removeable and this would allow better access to all parts of the back door.

If you can reach the wire which goes to the electric door lock, you could test if power is going through the wire. If no power when the unlock button is hit, you must trace the wire back to the switch.

Now if you put a 12 volt power source through test wires and bypass the locking mechanism and directly power the individual door lock, it should be possible to set the door lock to an open position. This would allow you to open the door and continue servicing the inside of the door.

To unlock the child lock, simply open the rear doors and look on the side of door for a small switch. Simply flip the switch and the child lock should unlock.

Open the door and look at the back edge of the door by the latch there will be a small sliding lever to enable/disable the child lock.

WIth child locks on, and door unlocked, you should still be able to open it from the outside of the car.

Back doors have a safety switch on the door. If it is what I think it is, open each back door from the outside and then flip the switch. Car washes are usually the culprit for this happening. As the car is being dried, they trip the switch and don't realize it.

Good luck.

If you want to keep the child-locks engaged, and doors unopenable from inside, you must set the lever by hand inside the rear door jam of each door. It should be marked, locked/unlocked or on/off. Are there other issues I am not addressing? I hope this was helpful.

Online tonight, TaterTodd