x2 i was having the same problem with my girls acura after i installed an amp and sub, the terminals were always corroded, if you twist the connectors on the post, you can sometimes find a sweet spot because it grinded away some of the corrosion, go to napa or schucks and buy some anti-corrosion spray, shit sprays out purple, and use a wirebrush and scrape the inside of the connectors and scrape the terminals, corrosion causes a barrier between the metals so the car doesnt start
