since you can jump start the car, it sounds like you have something jammed in the latch. You have to enter the trunk from the back seat. Open the first aid compartment. Get your hand into the trunk compartment. You should be able to pull the seat release or grab the cable enough to release the seat. Once you are in, you can work on the trunk latch. Many people keep one seat unlatched so that you don't have to go through this procedure.