You may have found yourself cursing the smartphone gods if you picked up a Nexus 6P handset only to have it eventually develop an annoying habit of endlessly rebooting. Known as the Bootloop of Death, users tried in vain to find a solution, but no amount of flashing, re-flashing, and wiping affected handsets seemed to cure whatever was ailing

Source: Hot Hardware – Here’s How To Fix Google Nexus 6P Bootloop Of Death Errors