My lift gate didn't like opening, either, so we managed to get the plastic panel off (somehow) and we attached some steel wire to the latch arm (I think?) and ran it up towards the back glass. That way, if my lift gate doesn't want to function like it should, I can just pull on the steel wire and it releases.
When I got my ZJ, I took it apart to prevent these woes, and then I ran a strong string up through the hole for the cargo cover, and attached it to a chunk of rubber. Now I can open the hatch from inside when camping with a tub on that string.