Possible ECU problem?
 

Have 2004 civic. The engine cranks only if the ECU fuse is removed - car will not start. When ECU fuse is replaced, the car will not crank. Battery is new, ECU relay is new, starter motor is fine (cranks well if ECU fuse is removed). Car worked fine a few weeks ago but replaced the head gasket and timing belt and now won't crank (and cannot shift out of park). Cannot find any blown fuses. Ground connections are complete and show 12.5 v.
Looking for ideas - hope to not have to change ECU