Sorry for the delay, I haven't been checking in this thread too often.
If *no* commands work, the system might be in Prod mode, which is unusual for kiosks.
What firmware version is displayed on the kiosk settings menu, if any?
I have the same issue as CosmoCortney with my CAT-SES Unit.
I can only send "cos help" and the commands that are listed. sdkversion and launch are sadly not in that list.