OR, if you are using a smart charger, it may have a mode called "recondition," or some such. You could try that. It would probably take several hours to go through that procedure, as opposed to a quick jump start.Hi Rick!
Are you using a "smart charger"?
I ask because some of them don't work well bringing a truly dead battery up. I've even seen some incorrectly "assume" it is a 6V battery and won't charge past that point.
The old fashioned ones that are just a transformer and rectifier seem to do better in the truly dead case. Then when you get it near 12V use the smart charger to finish or not if you aren't using that type.