I just took apart a battery backup surge protecter and I want to keep the lead acid battery and charger except the battery is bad. I tried leaving it to charge for a while, nothing. I filled the battery compartments with water as a youtube video suggested, still nothing. I've left it to charge for hours, but it only reads around 2 volts and doesn't get any higher. Any suggestions on how I can bring this battery back to life? Or if it's just a dud.