Dbar

Hey all this is my first post, owned the 2001 impreza non turbo ej201 for 3 months now, been off the road for a month whilst I've been changing the suspension, came out this morning to start it, it was frosty, first this year, basically its turning over but not starting, I have no lights on dash, the only one is the immobiliser until I disarm it, no mel, nothing. Also it has a aftermarket push start button as the ignition barrel went bad, so it got changed as I never had the £££ to get a new one. it's never gave me any problems before. I changed the battery last week as the old was on it's way out, all terminals look ok, no rust or corrosion. When I put it to the on position theres no noises and no lights but it cranks over just doesnt start. Cant think of anything else. Could it be a fuse or relay, so advise from people who know better will be greatly appreciated. Been bringing the car back to life as the last 10 years it's been abused and am at the point where it's all finished and then this this morning. What yous think and what do I look at to sorting this. Again thanks in advance for any help.