more info would help... what have you tried?
My first question would be have you ever even powered the mobo with a normal desktop atx psu?
get a multimeter and check the voltage coming out of the m1atx when the car is off/on... check the ign, 5v, and 12v lines...
ensure you connected the m1atx to the right pins for the powerswitch on the mobo.
as for the blinking light... check the mobo manual for what a flashing led means.. kind of weird it happens when the car is off. r u sure the case led is connected to the right pins on the mobo?