A guest has reported that their app is displaying an invalid signature error. 
This error is usually displayed due to lost internet connectivity.
In such cases, we recommend guest to delete the app, check the internet connection and signal strength (make sure that the device is not connected to any open Wifi).
Then download the app again and see if the issue persists.
If the issue is still persistent, please log a ticket with the Punchh Support Center.
Please be sure to indicate that you have already followed the instructions outlined in this article.
We will need to know the device details (Model name and OS version) of the device guest is using to investigate this further.