2002 chevy tracker, my back hatch will not open...any clues??? just bought ituse

I just bought an 04 Tracker and have the same issue, though I'm not sure how good this answer will be for your model. The linkage with the door and lock are worn, specifically the locking mechanism. You can take the back hatch door cover off and see the linkage working when someone tries to open the door. Have someone try to open the door while you are looking into the linkage area with a flashlight and you will see where it is being blocked. Simply move the linkage with your finger and it should open. Then, if it is the locking mechanism causing the issue, the hatch will open and close normally until you lock it again.