Goes through charging process Red light blinks then green light blinks like it is charging then after a few seconds solid green as if fully charged but it is still dead

I had the same problem. Your battery sounds like it got drained too much. The voltage on the battery is too low for the charger to charge. I looked on YouTube (how to charge battery that won't charge). I actually tried this today. I had a battery attached to one of those flashlights from a combo pack and the battery was drained down to 0.64v. The video I watched said take a higher voltage batter and boost it. Like a 20v to boost your 18v. Attach wires from one to the other. + to + and - to - I didn't have any. So what I did was stick 9v batteries together + to - in series I had 5 laying around. I taped a wire to the exposed terminals on the two end batteries and tapped the wire on the battery, which only brought it up to about 2.3volts. Then I just held the two wire on the battery for about a minute. It went up to about 6.3 volts I plugged it in the charger and it finally started charging. I don't know how well it will keep a charge. The batter is 10 or 12 years old. Hope this helps. And check YouTube. There is a lot of videos there.