This morning I went to turn my truck on and I got this message on the dash "Brake system failure, top speed 45mph" and then everything went dead.

The engine won't start, infotainment is dead, doors won't lock or unlock, no Brake lights (only two interior lights come on). I'm thinking dead battery but any info is welcomed.

 

that is a good place to start. measure the battery voltage with a voltmeter 12.6 is fully charged....12.0 is dead