I make up from your first sentence that you used another battery for your Pronto Pro NG before ad that the charging problem occurred right away when you charged the new battery for the first time.
If all this is right I would first try the old battery again. If the charging works well the old one, then it seems to be a problem with the new battery.
By the way I use different (especially heavier) battery's for my NG's. They work fine.