No start.

[John Cornforth]

Hi

Some "High Tech" chargers won't co-operate if the battery is too far discharged

Try an old fashioned one if you can. Once you get a bit of charge in the High Tech one may perform.

If you can't get an old fashioned one, even a 12 volt car battery via a 6 volt headlamp bulb (to limit the current) would do at a pinch.