I don’t know much about those terminals, but the screenshot hints at that (key=zeroes part), and then according to the diagram it waits for USB to flash new secure firmware and keys in case the terminal had to be serviced.

This root shell is probably not a security issue - and maybe even meaningfully user-accessible (for some fancier network configurations or diagnostics) - as, I suspect, it’s nothing more than a glorious modem for a stream of encrypted and authenticated data, plus a firmware updater (likely useless without a valid signature) - it could be potentially pretty much the same as hacking the upstream router. Sensitive (so there’s probably a sticker intended) but not something that breaks device’s security.