1. Activate developer mode in mobile device
Go to Settings > About and tap 7 times on Version.
2. Enable USB Debugging in mobile device
Go to Settings > Developer Options > Enable “USB debugging”
3. Connect tablet to computer
Plug tablet to computer using an USB cable.
Swipe down your Notification Area and select USB debugging connected
Make sure the checkbox next to USB debugging is selected.
4. Download custom recovery image in your computer
You need to download the image file (.img) that is compatible to your device.
Clockwork Mod Recovery
Unfortunately, CWM removed from his web the image download page (broken link). It looks as they want to encourage rooted app installation method instead of directly flashing recovery ROM.
If you are really interested in downloading CWM image, my advice would be to cross your fingers and Google it, or switching into rooted app installation.
TWRP
Visit this link and download latest version:
I recommend to go to ‘Devices’ > Look up your brand > Look up your model > ‘Download links’ > Download newest version
If your model cannot be found, then TWRP is not compatible with your device.
Alternatively, you can download a generic version for all devices from this link but it did not worked for me:
5. Download Android Platform tools in your computer
Download Mac version (latest was 28.0.2):
https://developer.android.com/studio/releases/platform-tools
Extract file in any folder. Take note of the path.
6. Test Android connectivity between computer and mobile device
Open a terminal, go to “platforms-tools” folder (wherever you extracted it) and run this command:
adb devices
Output may be as follows:
List of devices attached
015d30e122541a10 unauthorized
If this is the case, tablet must display a confirmation dialog to allow access to computer. Check “Always allow”and click “OK”.
Repeat the first command until you get an output like this:
List of devices attached
015d30e122541a10 device
7. Send command from computer to run mobile device bootloader
Run command:
adb reboot bootloader
Device screen must display a black screen with a disconnected Android robot.
8. Check that nexus 7 is in fastboot mode
Run command:
fastboot devices
Output should be:
015d30e122541a10 fastboot
9. Unlock bootloader
Run command from computer:
fastboot oem unlockfastboot
The correct output should be something as follows:
OKAY [ 0.000s]
Finished. Total time: 0.000s
Confirm on mobile device that ‘Lock state’ has value ‘Unlocked’. In the Nexus 7 fastboot screen lock state should have change to unlocked.
In case you get an error like the one below, run same command again:
(bootloader) erasing userdata...
FAILED ()
Finished. Total time: 31.319s
9B. Delete userdata (optional)
./fastboot format userdata
10. Install a custom recovery in Nexus 7
In this case, we will use CWT (Clockwork Touch) but TWRP would work as well.
Run command:
./fastboot flash recovery /Users/pablo/Downloads/recovery-clockwork-touch-6.0.2.3-grouper.img
It did not work on the first time becauase I received a timeout error. Is solved it by selecting the “reboot bootloader” option from the Nexus 7 options (using volume up/down and power button to select the command), then running again same command.
Sending 'recovery' (6530 KB) FAILED (remote: '(Timeout)')
Finished. Total time: 4.065s
Success message was:
Sending 'recovery' (6530 KB) OKAY [ 0.925s]
Writing 'recovery' OKAY [ 0.468s]
Finished. Total time: 1.451s
12. Run custom recovery
Enter bootloader:
- Either start up normally and them type ‘adp reboot bootloader’.
- On Nexus 7 (2012) device, press and hold Volume Down, Volume Up and Power buttons while starting to boot.
Then select ‘Recovery mode’ by selecting option with Volume Up/Down and then clicking on Power button.
External References
- How to Root the Google Nexus 7 on OS X by Rob Pickering.