Depending on the context, you almost certainly should show an error message (in order to reduce the likelihood of the user trying to use a function that is currently unavailable). If the context is very public and so help/support is generally unavailable, you probably should show a more general error like "Out of Order" if those features are core features of your product.
If not, the error message should be clear and prevent the user from attempting the broken function if possible, as in this example (where the "EFTPOS unavailable" sign is actually physically blocking access to the EFTPOS/card slot):
Image from SMH.com.au
If you do choose to show an error message, it's important to provide the right error message: simply stating matter-of-factly that an issue exists (as you have in your examples) isn't enough—you generally need to provide a call to action to allow the user to rectify the issue.
For instance, when our kiosk software loses its persistent connection to the server (something it needs to function correctly at all), the error we show says, basically:
This kiosk has lost its connection to the server.
Please reboot the kiosk or call the helpdesk on 1800 000 000
Notice that we tell them both what is wrong and what to do about it.