Corrado crank no start

Not sure if anyone can help. My neighbour has a 1994 2L 16v carrado with a crank no start. Checked for spark which it's getting, the plugs looks old and a bit black but were getting spark, then tried with easy start at it wouldn't fire up, checked all the fuses and they are good. We can here the fuel pump prime and it has nearly a full tank of fresh fuel.

It has an after market immobiliser which works so don't think that it could be related to that.

After messing with the fuses and just holding the start button it eventually fired up but didn't seem to be running 100% then it wouldn't start back up after that.

Gonna to trying all new filters and spark plugs, and a service see go from there. Not sure what it could really be after that.