When you say it won't turn over - do you mean you can hear it trying to turn but there isn't enough power in the battery or is there absolutely nothing at all happening? If you're not sure, put the headlights on and then try starting, if when you turn the ignition key the headlamps dim a lot then your battery hasn't enough power in it -probably because of what you've been doing with the speakers. (you haven't left a courtesy light on for a long time have you?) If the headlights don't dim then the battery's probably OK but you may have a problem with the starter system. Hope that moves you on a little!
Richard, December 2008
