Open the trunk and you'll see a wire loom there between the trunk lid and body of the car. Open the tape and rubber boot protecting the wires of this loom. You most likely will see some of the wires inside pinched, burnt, and damaged. If so this is what is causing your grief.
Looking at the loom from the outside won't help assess problems as most of the time the wire loom shows no signs of physical damage. If repairs are needed, disconnect the battery first before working on the car otherwise, sparks and smoke shows will arise.