[Tannaton]

A paddling pool inflator shouldn't have flattened a car battery in 9 minutes, unless it was drawing circa 100 amps.... So it was probably toast to start with especially if it was 11 years old.

I'd try a 24 hour charge with a battery charger, or get a battery test at Kwik Fit or Halfords. If you have a multimeter - try as suggested in the video above...