Nexus 5X and Nexus 6P smartphones have an hardware issue that causes “bootloop of death” (aka BLOD). This issue show Google boot-up animation till battery exhaustion.
If your device is still under warranty follow the the official Google Bootloop solution.
The BLOD was generated by an hardware issue on A57 cores of the SoC(two in 5X and four in 6P). The following fix disables A57 cores so your device will only run on A53 cores (four cores).