When I turn the key on, nothing happens. The instrument panel doesn't light up, the fuel pump doesn't hum and the green light on the circuit board doesn't light up. Fuses are not blown. Battery is relatively new and still healthy with 12.6 volts. Posts and terminals are clean. If I take the terminals off the posts and put them back on, everything lights up like normal but as soon as I turn the key, all I hear is a loud click and the machine dies. Then I'm back to square one. Any ideas?