>>What does “bricked” mean? That they’ve been programmed to not work?<<
Yes. The devices were wiped and the firmware remotely updated so they won’t even turn on. In many devices today this will happen even if they are not turned on (as the batteries are unable to be removed).
There might be some things like cables and speakers that will still work, as well as a few tablets but these days stores like that do not have much stock on hand.
At stolen in the box, they are not turned on, not listening to a network and cannot be updated. Not bricked. They cannot be connected to a cell network. They might connect to wifi.