I can't open rear door by fob

Sounds like a loose connection

 

But the window works at the rear door, correct? I did some research on that since I have a similar problem -- can put rear window DOWN from driver's door but not UP.. I think I recall that generally the issue is in the switch assembly at the driver's door. Personally, I just put a wide piece of clear tape over the driver's door rear switches.

 

Check the following "safety" settings

1) is the child lock "on" for that door? If so, it may cause some of the symptoms. Child lock is on the edge of the rear doors, designed to keep kids from opening the door while the car is moving.
2) Is the "window lock" activated? That's a button on the driver's door.
3) Opening the rear door via FOB. On mine I have the car settings arranged so that the rear doors unlock when I press the "unlock" button twice in succession.