Showing posts from 2021

Recover Nexus 9 lost in a boot loop

 My old Nexus 9 tablet was caught in a boot loop: it would boot up, then freeze, reboot, freeze, ... until the battery was exhausted. The instructions at  stackexchange  helped a lot. Here is a summary of what I did: Download the latest OTA file from Google's Developper site . This is a zip file. Do not uncompress it. Reboot in Recovery Mode. For the Nexus 9, press the power and volume up buttons until a menu appears. Choose Recovery Mode. Once in Recovery Mode (recognisable by its Android mascot laying on its back), quickly press the Power Button and Volume Up to enter a hidden menu. Choose "Apply update from adb" On the computer, run "adb sideload <>" After the update is done, choose "Reboot system now"

Loss of Administrator access after upgrade to macOS Big Sur

 It appears that in some cases the upgrade from macOS Catalina to macOS Big Sur causes a user with Administrator access to lose these admin privileges. One of the main symptoms is the inability to unlock the Security and Privacy System Preferences app. There is a thread on the Apple developper forum that describes the issue and provides possible fixes: Reset the SMC. This actually worked in my case, and I didn't try the other proposed fix. Reboot in Recovery Mode (press Command+R right after turning the computer on), open the Terminal (using the Tools menu) and delete /Volumes/Macintosh HD/var/db/.AppleSetupDone