[donalduck_69]

Removing tint is the biggest bitch in the world. I should know, I do it for a living. And of course, the hardest and messiest of all is the back window. I would start by removing the deck lid (you know, the carpet on top of the speakers) then peel the film off as I'm sure you did on the rest of the windows. Then soak the shi* out of the window with some sort of glass cleaner (provided it has ammonia in it, Zep works really good) or fill a spray bottle up with Isopropyl alcohol and water (about half and half and make sure you have some good ventilation cause that shi* will make you sick fast. Then after you've soaked in it whatever, get one of those plastic scrubbers that people use for washing dishes. Scrub the window and scrub some more. Clean the loose glue off with paper towels or whatever and do the whole thing again as many times as it takes. After you're done with that, very carefully, using a razorblade, scrape any excess glue of the window in between the defroster lines. That should leave it nice and clean and ready for retinting. To answer you're next question, those electrical things are for the defroster. If all of that stuff fails, take it to a professional like me and make me do it (you bastard, just kidding). Good luck.