First measure the battery voltage with a cheap digital voltmeter. If it's less than around 12.4 - 12.6, recharge it and try to start it again. If it's around 10.0 - 11.5 volts, there may be a dead cell in the battery. With low voltage, some of the computers may have a hard time powering down. With all the complicated computers on cars today there can be all kinds of odd things happening when the battery is weak.
Does the clicking stop after about 20 seconds? If so, it might be normal. Some emissions self-tests are run by the engine computer after you turn the ignition switch off, but usually the engine must be warmed up for the tests to run.
When you try to start the engine, what happens to the lights? If the dash lights get real dim, you have a weak / bad / discharged battery issue or dirty or corroded battery cables. Watch the headlights while trying to start the engine. If they go out, look for the battery issue.
Do you hear one loud metallic clunk when you try to start it? That is likely to be bad contacts in the starter motor solenoid. They are very inexpensive, and a competent do-it-yourselfer can replace them. If that's the case, I can copy and paste repair instructions.
If the battery voltage measured ok, but the headlights go out when you crank the engine, re-measure the voltage on the battery posts, (not the cables), while someone cranks the engine. If the lights go out but battery voltage stays above about 11. 0 volts, you have bad cable connections. Clean the battery posts and cable ends. NO SPARKS OR FLAME in the area of the battery; they give off explosive hydrogen gas.
Holler back after you make some of these tests.
Saturday, March 28th, 2009 AT 2:12 AM