Android 6.0 drains my Nexus 5 battery within an hour

So. This morning I received the OTA update for Android 6.0 on my Nexus 5. Previously had no problems with battery usage, but after installing the update my battery is drained within an hour, without me using the phone in any way.

The settings indicate that the Android Core Apps are the cause of this and when I press the information icon in the top right it shows 'Contacts Storage'. I have to say that also since the update, my contact list is empty and keeps showing the message 'Contacts are being updated'.

Any clue on how to solve this issue?

Answer

I'm guessing this is being caused by a glitch in Google's sync services. This can be a difficult fix if there are more underlying problems, however clearing the system cache will likely fix the issue.

1. Turn your device off.


2. Press the power and volume down buttons at the same time for about 4 seconds. Release. A barebones menu should appear.


3. Use the volume buttons to scroll to recovery.


4. Open the recovery menu and press the power button for one second, then continue to hold the power button and press and hold the volume up button for 3 seconds. Release. This can be troublesome so if you have difficulty Google "Clear System Cache Nexus 5".


5. Scroll to Clear System Cache or something resembling it. Be careful what you select as a lot of device wiping commands are in here.


6. Let it go, then select "Reboot normally"

If that does not fix it, you may need to do a factory reset. You would stay on Marshmallow.