I may be able to help you here, since I went through this about 6 months ago
First off, the lift gate on my
'99 would not open, yet the window would. The lock for the window was fully functional which gave me every indication that the power lock was fine. Here's what I found during troubleshooting:
I lifted the rear glass and pryed back the plastic interior panel on the lift gate, being careful not to break the panel, and trying not to distort it too badly. Focus your attention on the area just below the window latch. Below it, inside the door frame, there are two threaded rods. One is about 4" in length and dangles from the lift gate door handle. The other is significantly longer and extends upward from the lift gate latching mechanism. The two are
supposed to be connected via a little clip made of yellow plastic. Somehow, the plastic clip on mine had opened up and disconnected the handle from the latch. The door handle felt like it was locked (e.g. no tension when I tried to open it)... but it was actually just moving freely inside the door.
To fix it, I worked my hand and forearm in between the panel and the door (NOT comfortable at all) and used a pair of needle-nose pliers to grip the threaded rod for the latch. It is a pain in the ass, but take your time and make sure you have a good grip on the rod (AND MAKE SURE THE DOOR IS UNLOCKED
) Pull upwards on the latch rod with the pliers, and the lift gate should open.
With the lift gate open, you should be able to remove the interior panel completely. Remove the two screws that attach the interior handle, and the rest of the interior panel is held in with plastic and metal retaining clips. At this point, it's a piece o' cake.
Luckily, the plastic clip on mine had just popped loose. I simply inserted both threaded rods back into it, and snapped it back together.
The most difficult part is using the "needle-nose plier manual override" to open the lift gate in the first place
Hope this helps you out.