If you’ve went through the situation, that your beloved tablet started to work terribly after update, I’ll simply sketch the solution. My problem was update from Android 4.4, to 5.0 Lollipop (https://www.youtube.com/watch?v=3rYoRaxgOE0). I went through some of internet tutorials, but they seem to be quite complicated, but the core of the solution is very simple.
Beware: You will lose all the data; but it’s nice to start fresh. (but backup)
In short, you 1) put the device into boot menu, 2) unlock it and 3) upload images using fastboot. Have your device connected using USB.
Instructions:
1) put your device into boot menu; you cand find specific instructions on google (nexus 10: hold together Power + Volume Up + Volume Down until you enter boot menu)
2) the unlocking is done using fastboot
i. you need to download it. it is part of android development toolkit, but you can go with minimal version here (for windows, aargh), or check this official android page. you will download much more than necessary, but whatever.
ii. find fastboot and run on command line “fastboot unlock oem” if it works you, you’re fine; if not, try some re-connections/restarts or search for another help.
3) download official factory image of interest (nexus; check device id/name; i had to select mantaray image), unzip and run flash-all script.
flash-all script assumes that it has fastboot available. in linux, just put it to /usr/bin (or there are many options); in windows either update PATH, or just copy it into system32 folder of windows.
That should do the job.
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