I'm trying to do a sound system upgrade so I gotta pull the rear speakers out in my convertible, but the driver's side rear seat won't fold down. I've tried everything, from unlocking the seat by the headrest, shaking it aggressively, pulling on the cable with some pliers but no luck.

I took my car to a body shop today and they quoted me almost $500 to fix it. Is there a better way to go about doing this? Honestly, I don't care if the seat folds down normally or not. I just need the latch to release once so I can access the rear speakers. I've looked for disassembly instructions but I'm having a hard time finding anything. Any thoughts or ideas?