Android M
Android M to introduce Google’s new Boot Verification System (beginnerstech)

Google is reportedly working on a new Boot Verification System that checks the integrity of your Android device software at each startup, according to a recent post on the company's Nexus support site.

With the Android M release looking imminent, it is widely speculated that the latest changes incorporated into its boot system verification will include a bunch of colour coded error messages to help users identify the root cause of any issue linked to the mobile operating system.

Android M Boot Verification System
(Google Nexus support site)

For instance, a yellow exclamation mark followed by the error message: "Your device has loaded a different operating system", indicates that some unofficial ROM is installed on the device and there is no need to take any further action.

Furthermore, an orange warning icon suggests that the device cannot be verified for corruption, which can happen if the device's bootloader is unlocked. Just lock the bootloader of the device or ignore the error message, if you see this warning.

Finally, the red symbol indicates that your device is corrupt or it cannot be trusted and may not work properly. Such an error symbol could be the result of modifying the stock firmware that might have created inconsistencies with the boot verification system or corrupted some system files.

These messages can be dismissed with the press of the Power button, if they do not disappear within 10 seconds. Although there are no further details provided about the technology used with Android's system safety warnings, folks at Android Police report that it is based on dm-versity, which debuted with Android 4.4.