Raven xt

I have 3 units in the field that stopped working,the lights on the Raven xt is solid power and slow blinking network lights, Can anyone tell me what that means? In the manual the only thing that remotely looks like what i’m seeing is SOS mode,whatever that is. Its connected to a Mercury instrument and the Raven has a sim card installed, I believe it is a straight pipe through for communication. We have 900Mhz radio’s (!400 or so) and maybe 200 Ravens in the field on the ATT network.