If tech has proper tool, tech can read the status of the door latches (door ajar DTC) and all DTCs associated with the MS-Can modules. Did he do that? The ForScan App for Smartphones with proper OBDII plug in adapter (eg, OBDLink MX Elm327) can read all HS and MS Can Modules.
If doors aren't closed you should also see it on the intrument panel. The Door Modules and the Liftgate Trunk Module have their own Fuses which are hot all the time. So, I doubt all Modules have blown fuses. If the command is not going through to the door but did to the Trunk, then perhaps there is a problem with the MS Can at one of the connection / splice points. The Body Control Module would send the commands over the MS Can to the Modules.
Lastly, as homestead mentions, perhaps something is amiss with an input to the BCM preventing operation of the door locks. Does car finder work: from the manual,
Press the lock button on the key twice
within three seconds. The horn sounds and
the turn signals flash. We recommend you
use this method to locate your vehicle,
rather than using the panic alarm.
Note: If locking was not successful or if any
door or the liftgate is open, or if the hood is
open on vehicles with a perimeter alarm or
remote start, the horn will sound twice and
the lamps will not flash.
Sounding a Panic Alarm (If Equipped)
Note: The panic alarm will only operate
when the ignition is off.