At times this is very needed, esp around updates etc. Esp when you’ve done a factory reset and you still have problems. Seems to be esp useful around battery problems. This the OLD version of this guide. Newer one is HERE.
Edit: this is the OLD article on it. It’s however been changed since then, which I’ve covered in later articles. It’s no longer this method on M8 with Marshmallow, which I’ve covered HERE.
Just to make things clear: this do NOT delete any personal data. This “just” clears the cache partition.
First you have to get into bootloader mode. I prefer option B myself since it’s lazy. You can use any of the options below, you don’t need to use a computer if you don’t want to. It’s there to show all the options.
- Turn off Fast boot under Settings > Power
- Power off phone
- Press and hold Vol down , press power button until you see bootloader (3 happy androids on skateboards at bottom of page). Release vol down.
Connect phone to computer with USB cable. Make sure it’s connected with
Do a reboot with
ADB REBOOT BOOTLOADER
If you used Method B:
If it says FASTBOOT right under the phone info (about radios and such). Then make sure that BOOTLOADER is selected in the list below, use Power to select. Which will open the Bootloader menu.
- Select Recovery by using vol down, press Power to select.
- Wait. This takes a while.
- You will see a red triangle with a exclamation mark in the middle.
- Press and hold Vol up. Tap power. Release vol up when you see a blue menu.
- Select Wipe Cache partition with vol down. Press Power. Now it wipes the cache partition. Done!
- It should now have marked Reboot system now. Press Power to select. Phone will now reboot to normal mode.