Unless a fault code is generated, or you see a message at the upper left of the screen that we can go from there is not enough to go on.
With that in mind, run a Software / Network Reset and try again.
This is done at the copier by logging on as the admin, select Machine Status > Tools > Troubleshooting > Resets and choose the option that resets both (No settings will be lost) then try a scan.
If that fails, update the firmware to the latest, see if that fixes it.
If all fails, you likely need somebody onsite to troubleshoot.