If having trouble with Technicolor/Cisco/Xfinity Model DPC3941B Wireless Gateway (Modem/Router combo)
See this page: https://fullsteam.zendesk.com/hc/en-us/articles/360030991032-How-do-I-setup-an-Ingenico-iSMP4-wireless-terminal-device-
Before using the iSMP4 device for the first time, Ingenico recommends to charge it for a minimum of four hours.
When the terminal is not in charging mode, one can power off the terminal by simultaneously pressing the “#“ + yellow keys for several seconds.
See the following images for help with navigation & functionality of the device: