Rear hatch lock opening when hatch is open and rear wiper quit working at same time lock started acting strange...

SOURCE: Rear hatch won't open

There is a little plastic circle on the inside trim, near the bottom of the rear hatch. Pop this off, and you can get a finger inside, or better yet a screwdriver. There is a metal piece labeled L3, I believe. It doesn't take much pressure, but you must manually push this and it will release the lock, and you can push the door open.

SOURCE: the rear hatch will not

There is a switch under the handle you press to open it.
If pressing it and you don't hear the solenoid click you have bigger problem then lost fob
Take it to a dealer to be serviced

SOURCE: 2005 Buick Rendezous rear hatch

If the remote opens the rear hatch your problem is likely the button on the tailgate itself. I replaced mine on my 2005 about 3 months ago for the same fault.One problem you may have replacing the button could be that the screws are corroded and difficult top remove. Other than that it is a pretty easy fix.

SOURCE: rear hatch wont open - all other doors unlock and

I have a problem the back door will not open with key remote or just by the touch pad. That I know of is there a release button or something to open the back hatch.