Help Can't update Android - acts like it's updating but reboots into same version it was on before

[Android Question]

I have a Nexus7 (K008) that needs to be updated to 6. It is currently on 5.1.1.

The device will show the update to 6.0.1 as being available, I click to download and it downloads, and then when it's ready, I click to install it. That's where there's a problem: it will act like it's updating, restart, etc., but when it finally finishes, it will have booted into 5.1.1 again.

If I go back to the system info it will say for a while that my device is up to date (and clicking check for updates will not find the update) for several hours. Then it will find the 6.0.1 update again, download, act like it's installing, etc. - but repeats the cycle of "finishing the update" only to boot into 5.1.1.

I had this issue on another device of the same kind and found information online about fixing it by clearing the cache (and maybe something else) of some specific Android process. However, I don't remember which process it was and the forum I got the info from has closed.

I would appreciate if anyone might know the fix I'm talking about and can point me in the right direction. Thanks.

 

[scary alien]

Welcome to AF

Have you rooted or otherwise modified your device?

 

[Bearsyzf]

do you have sufficient space for the update ?

 

[epcheney]

do you have sufficient space for the update ?

Yes - device is completely wiped.

 

[epcheney]

Welcome to AF

Have you rooted or otherwise modified your device?

I don't believe so but will check. Thanks for the welcome!