Comments On Trouble Symptom
WARNING: This page is about a different car, the 2014 Mitsubishi Outlander. However, it is still accessible from the selected car via links, so may be relevant.
There may be a malfunction in one of the followings; the wiring harness or its connector(s) between the power liftgate control unit and the half latch switch, the wiring harness or its connector(s) between the power liftgate control unit and the full latch switch, the liftgate latch switch itself or the power liftgate control unit itself.