check engine light comes on then flashes and turns off. is this normal? on 2002 Honda Civic

My civic wornt start. i checked the timing 3 times. There is fuel pressure at the fuel rail. My c.o.p. are getting 12 volts.I have compression 110 psi. I just did the head gasket and now it cranks but wont start, doesnt even attempt to start. The check engine light will turn on when i put the key in and turn it to ignition. stays on for 20sec. then flashes 5 times and turns off. Once i turn the key to start the car it cranks but no start. When I turn the key back to ignition the check engine light is off and the battery light is on.

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1 answer 3 comments
First- recheck your timing. Second- why was headgasket replaced? Overheat, oil leak,broke timing belt & bent valves?
yes I have checked it 3 times. It overheated.
is the immobilizer (green key) light flashing?
No it comes on when turned key to on position and goes away. it only blinks after I tun off and remove the key