The specific meaning of the failure display of BIS V series processors
For BISV series processors, pay attention to the RD display light and the SF indicator light. 
In general, the absence of the RD display light and LED light indicates that the BIS V device is not ready for operation.
The SF light indicates that either there is no voltage or that the bus communication is not established yet.
If the SF light is a constant bright red, it indicates that the bus communication is not ready. A red flicker indicates that the DCP signal service has started.
Learn more about the failure status of the BIS V series processors