i have 2, saddly neglected UPS's, both have had bad SLA's for quite a while, well..... i attempted to replace both SLA's & found then when i unplug the UPS's, they fail to power off the SLAs. YES they are fully charged, and of the proper A/h OR higher..... just go dead when unplugged. checked fuses, checked charging and get charge power when plugged in, just 0 output when in UPS mode. any suggestions?