I had a dead battery a year ago after leaving the lights on. It was only 2 years old at the time. I connected my Schumacher maintainer and it charged after a few hours. Fired right up and I haven't had an issue since. BTW, if I'm not going to drive for a few days, I connect the maintainer. And of course it is always connected when the car hibernates over the winter.
thanks, all, MUCH appreciate the advice. I found a decent slow charger to borrow, so I might as well give that a shot.
Unsure how old it is - bought car used - so I shall check on that as well, and replace if needed.
There should be a sticker on your battery that shows when the battery was manufacturer. It can say the month and year (April 2014) or some will have digit code like tires (example: 4018) which means it was manufactured during 40th week of 2018. If your battery is more than 5 years old, it might be time to replace it after this incident.