Device stuck in boot loop What should I do if my Android takes a long time to boot? It just shows the boot animation constantly. It has been running for 2 days just displaying the same power on animation.
Your device is in a bootloop. Check boot-loop tag info. Boot loop usually happens when you flash a ROM that is not compatible with your kernel, or you delete a file that is crucial to the booting of your device.

If you're rooted, you can try entering the recovery and flashing the ROM again (with correct files this time).