[bingisSD]

well last week i had the exact same problem on my hatchback, and it was my battery, i was miffed. I did some voltage tests (14.9volts with car on) and 9.2volts and dropping with the car off and key out of the ignition. with the key in the ignition the voltage dropped to an astonishing 8.5volts. I recieved a jumpstart and went to my local auto parts store and had them run an 'alternator test' and they told my cheap ass to buy a new battery ecause it had bad cells. i havent had to get a jump start yet. I doubt you have a faulty relay. "...all things the same, the easiest solution is usually true..." - unknown
at least try p utting a different battery in youre car and making sure it is grounded and charged properly, reset the computer, and start from scratch again.