I would only buy a VOOM box from a private seller and one who also makes it specifically clear that the box was up and running with VOOM service up until their shutdown. If they don't say it's was working and still works for OTA, move on to another one.
The reason I mention a private seller is I mean vs a "store" type that buys up lots of items. They will often avoid the issue of OTA service and just mention "New, still in original box. Includes all cables, remote, etc, etc". They aren't doing anything wrong, of course, just selling a box that has literally ZERO value to most people.