The manual says that if the display is blank and no LEDs are showing, either the unit is not powered or the mains has failed and the batteries are lower than 21 V. To recover from the low-battery shut-off, power down completely, check the batteries are no lower than 21 V and power the system up. If the batteries are lower than 21 V they should be replaced or monitored during initial charging to ensure they recharge correctly, which could take several hours. If the batteries are below 18 V they should be replaced, as they will have lost much of their capacity and are unlikely to recover.
Yellow EARTH FAULT indicator, flashing: the manual says an earth fault has been detected where a path exists from the circuit wiring to earth. Remove circuits one at a time to discover which one, and then rectify.
Yellow FAULT indicator, continuous: the manual says the control panel is in the fault state and other indicators will show the origin. The indication can also be confirmed from the message in the panel information screen or the relevant event log.
Yellow FIRE OUTPUT indicator, flashing: the manual says a fault condition is present on a monitored relay circuit. Continuous means a device or an action associated with the monitored relay circuit has been disabled.
Yellow POWER FAULT indicator, flashing: the manual says a mains supply fault has been detected, and to check for a 230 V AC supply on the incoming AC terminals.
Yellow SOUNDER indicator, flashing: the manual says a fault condition is present on a monitored sounder circuit. Continuous means a device or an action associated with the monitored sounder circuits has been disabled.
Yellow SYSTEM FAULT indicator, continuous: the manual says it indicates the presence of a processor or a checksum error. To clear it, power the system down, reprogram all settings and test the system. During a system fault, depending on the cause, all relays will be off, all zones powered down, and the zone, power fault and disabled LEDs on continuously (page 14). The panel should be powered down for approximately 2 minutes and re-powered by a competent person and the event entered in the log; if the panel appears operational, a reset will clear the fault (page 14).
Twinflex Pro: SYSTEM FAULT LED (flashing, write enable)
Yellow SYSTEM FAULT indicator, flashing: the manual says this LED is also illuminated if the write protect / write enable switch is left on while the system is not in the engineer menu. In access levels 1 and 2 a system fault is then shown on the LEDs and display and the fault relay is off, but it has no effect on the operation of the panel and serves as a reminder to switch write enable off before leaving the panel (page 14).
Yellow ZONE indicator, flashing: the manual says a fault condition is present on one of the zones or on a device connected to that zone. Continuous means a device or an action associated with a zone has been disabled.
Records marked “sourced — not yet independently verified” carry a real citation but have not yet completed formal review. Always confirm against the manufacturer's current documentation before acting on site.