Welcome to the Forum from NH.
Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.
I hope that you will become a participating member in the Forum's discussions.
Pics of the truck, please.
Near the bottom at the center (left to right) of the inside trim panel of the lift gate door, do you see a small (~1/4 inch) dot/mark/impression in the plastic, like it was meant to be there in the original mold? If yes, take a 1/4" drill and carefully drill through that dot. Then, you can use a skinny long screwdriver in that hole to open the latch mechanism of the lift gate door.