Ka help needed

[Looneybry]

I have a 96 240sx with a KA24DE got in a front end accident a while ago , i replaced everything in the front end (rad support , rad , ac components headlights , hood , fenders , bumper ). Now that everything is hooked up it wont start up. I bought a new battery, pulled out starter tested it came out fine, replaced fuel pump fuse. Sometimes it will crank but not start and sometimes it wont even crank. everything else like lighting, alarm, and radio work. I had a mechanic(not that experienced i could tell) come by and he seemed to think it was the security system with a kill switch. he also said the distributor wasn't giving power to spark plugs (working on getting a new one) but he thinks its the kill switch preventing the distributor. so i took out the alarm system and still nothing. i recently found something odd, whenever i moved the engine bay fuse box to the left the engine would crank but still not start? with no one in the car or pressing the clutch or turning the key?? so please help i spent countless hours and money on this confusion! feel free to text (562)4seven7-19six9
located in long beach if you can or want to help or take a look