What this feature does is limit the One M8 from connecting to a network and bring a new homescreen (above) which only includes the dialer, text, calculator and calendar apps. You will be able to use the phone for over 15 hours on only 5% off the battery life. When turned on, this mode will do the following:
- Conserve CPU usage
- Reduce screen brightness
- Turn off data connection when screen is off
- Allow only essential apps to run
- Turn off pedometer
It should take about 5-7 minutes to install the update. You should connect to your WiFi network to avoid any interruptions.