Engine died

U first need to identify the problem. Is car turning over or completely dead. If it is dead, it's related to weak battery, dirty or corroded battery cables, bad starter or ignition switch but nothing to do with gas, spark plugs

Neighbor tried it out and said it kicks over and then dies out after 2sec and reckons it might be the main relay

If you don't hear electric gas pump when you turn key to On, it's likely the relay. My 87 Prelude Si had that issue. Located on left side of driver's foot-well on that car. I could usually get it to click by tapping on the box. Issue is bad solder joints. If you're handy with soldering iron, it's a DIY (de-solder, re-solder the posts to the circuit board). Search online for more info, pics....