[jclark003]

If the sw update doesn't work, start looking at the ap computer to see if it has power and no fault lights. For many newer ap's, Power for the head unit is supplied by the N2K network backbone whereas the AP computer requires a separate supply. If the computer isn't getting power, the head unit, which is getting power from the network, won't see it and may be the error you are seeing. Tiara usually has an autopilot override switch that cuts supply voltage to the AP computer. Possible the switch is bad or isn't getting power due to a breaker being open.