Hey guys I'm having some issues with power to the rear end of the car.

First symptom was the back up lights no longer work. Second is my brake lights pulsate instead of remainimg steady when the brake is being pushed. Third, and most wierd. The turn signals flicker and dont work for a minute after starting the car but begin working fine shortly after. Also during this period I wasn't able to open the trunk.

This is on a 2012 mustang convertible that I bought used a few months ago. I believe the trunk is leaky so could it be a short causing this? Thanks