If you want to come out from ultra power saving mode, tap on more button, i.e., to the top right of the device and click on disable ultra power saving mode. (phoneradar.com)
To use this feature, Open the recent menu and tap on the pin button that is on the bottom right of the device and tap on yes. (phoneradar.com)
You can also use the main navigation wheel on the lower right of the device's keyboard to turn pages. (the-ebook-reader.com)