CMM1000/1200 Mower Problem

[hammertoe27]

I am in a desperate situation of potentially buying a new lawn mower if I can't figure this out. I had the battery replaced on my CMM1000/1200 lawnmower (the top sticker says 1200, the back placard is stamped 1000, so I don't know what it is) about eight years ago. It finally wasn't charging, so I assumed it was the batteries and got a Mighty Max ML18-12 Int 12 Volt 18 amp battery set. Installed it and it wouldn't charge. The indicator light would start red, but a few minutes later it would show green. So I assumed that the charger needed to be replaced. I bought a knock-off charger from eBay that fits the model of my mower. But if does the same thing--starts red but then goes green a few minutes later. I just plugged it in so will see if it charges overnight, but I'm guessing it won't charge. What could be the problem?

 

[hammertoe27]

I think it's something internal that I am unable to fix, so I bit the bullet and moved on.