The device keeps cycling between the blue Ingenico Screen and a blank blue screen
When this happens, it's likely that the battery has run low and it's nearly dead. When this happens, plug the device in and let it charge up. Once it reaches the sufficient battery life, restart the device and the problem should go away.
Before using the iSMP4 device for the first time, Ingenico recommends charging 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: