The fire alarm controller has an electrical fault
The alarm, the power supply plate and the charging circuit are damaged and can not be charged. The battery voltage is too low and the device is reported to be out of order.
Battery damaged, not charged.
When the battery is connected to the power panel, there should be a fuse. Check to see if the fuse has blown. (look at how long the alarm has been running for a long time, if the battery is damaged)
