I've been through the same exact problem that your going through right now and im gonna try to explain to u as best i can.
The way the latch works is that the handle, that u pull on to open the trunk, is connected to a rod and this rod is connected to the latch at the base of the trunk door. So when u pull up on the handle, the handle pulls up the rod and the rod releases the latch. The handle and the rod are connected together by a pin and what happen in my situation is that the pin snapped. Now that there is no connection bet. the handle and the rod the latch cant be released. So you'll have to access the handle through the inside of the Jeep.
The way i did this is that i removed as many screws as possible on the interior panel, throught the inside of the jeep. Then i gently pulled on the top part of the panel, just so i can see inside, and with a flashlight i located the rod that is connected to the latch. Then with a wire hanger i hooked onto the rod and pulled up on it, and the trunk door released. Then, I finished taking the panel off.
Now you can buy a new pin but Jeep wont allow u to buy just the pin, you'll have to purchase the whole handle assembly, which i believe they wanted $90? I wasn't gonna spend all that for a pin, so what i did is that i reconnected the handle and rod together with a heavy duty thick wire, and it worked.
To ensure that the wire wont break and this wont happen again, I always keep the latch lubed by applying grease to the latch every once in a while, in order to reduce the tension on the connection bet. the handle and the rod.
I know your worried about breaking the plastic, but the only way to get to the handle is from the inside, so be very cautious and try your best not to break it, easier said than done. Hope I helped and good luck.