Electrical issue - need help please

[2700gavin]

All following on from my pervious engines demise popping a con rod whilst in the motorway , I now have my new engine fitted. The only problem it won't fire up, turns over ok. We did have a problem last week with the battery. Now, this as my mechanic told me the second battery he has found in as many weeks. With my car being stood for so long I had to take the battery out of the car and place on charge. Battery fitted Thursday last week , had been on charge for 4 days. Try and start the car and blue the 120a fuse and the fuses to the clocks etc and abs pump buzzing , weird until he checked the battery , it had reversed its polarity !!!!!. Have now put new battery in and won't fire. Have checked the coil packs power going to them but not sparking. Have tried the other set of coil packs I have and still no spark. Do you think I may have damaged the ecu ? Is there anything else to check , my mechanic is scratching his head a bit.
If it is the ecu does anybody have one I can try to eliminate the problem ?

[Davezj]

Have you gone through and pulled and check the resistance of the all the fuses, under bonnet and in driver footwell. some fuse can blow in such a way that looking at them is not enough you need to resistance check them, and remplace any that have blown.

then what happens.

what happens when you turn the ingtion on and don't crank the engine over, do the dash light come on and go off as normal, or is everything dead?

[2700gavin]

Everything is on , all dash lights now back on. Have tested all fuses in both footwell and under bonnet and all tested ok. Checked to see if getting a signal for crank sensor and all is good. Not. Sure what else to check ? We've checked everything over on alarm and immobiliser as that caught me out out last time and all is good there. Do you think it may have damaged the ecu ? Or is that what fuses are supposed to stop ?

[TAR]

check the ignition failure sensor?

[Davezj]

well if all the dash warning lights come on when you turn the ignition on and go off correctly, you can try reading the error codes in the ecu, if it give you some logical error codes and not just random flashes then that is a start.

the error codes would be my first point of looking at.

[Davezj]

ignition fail sensor is on the top of the front rocker cover if you did not know where it lives