[Nexus 7 Q&A, Help & Troubleshooting] GedBlake:
No, problem Anderson2... glad to help.

Adb and fastboot are indeed powerful and useful tools, and I would strongly recommend anybody wishing to 'modify' their Nexus 7 (everything from rooting to flashing Custom ROMs) to familiarise themselves with the fundamentals of their operation... rather than relying on toolkits.

There are actually ways of flashing TWRP or CWM Custom Recoveries directly from the Nexus 7 itself, without recourse to either fastboot or the need for a PC... by using apps like

Flash Image GUI

or

Flashify

. But these apps need you to be already rooted, unfortunately:(.

So to summarize how to acquire root the old fashioned way....

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1). Unlock the bootloader first with fastboot oem unlock. For security reasons, this will factory reset the device... ie., WIPE everything on it.

...but I assume your Nexus 7's bootloader is already unlocked, given it's been rooted once before.

And so swiftly skipping forward to step 2...

2). Fastboot flash a Custom Recovery (CWM or TWRP) with fastboot flash recovery recovery.img... where 'recovery.img' is the Custom Recovery of your choice. Reboot the device by using the Custom Recovery's own reboot option.

3). Download

Chainfire's UPDATE-SuperSU-v1.65.zip root package

directly to your Nexus 7. This DOES need to be on the Nexus 7. Most Android browsers (including Chrome) download stuff to the /download folder on the devices internal storage. You'll need to remember the location, for when you come to flash it with either CWM or TWRP.

4). Boot the Nexus 7 into the bootloader. Although you can do it with adb reboot bootloader, you can also do it manually as follows...

- Shut down the Nexus 7 completely.

- Press and hold the VOL-DOWN button... whilst holding, press the POWER-ON button for about 5-10 seconds. The device should now boot into the bootloader.

5). Boot into your Custom Recovery... whilst in the bootloader, use the VOL-KEYS to navigate to the RECOVERY MODE option, and press the POWER BUTTON to select. The device will now boot into either CWM or TWRP Custom Recovery.... whichever one you fastboot flashed earlier.

6). Now to ROOT!

** If using TWRP... tap on the INSTALL button, and then navigate to the /download folder on the Nexus 7's internal storage, and where Chainfires UPDATE-SuperSU-v1.65.zip is awaiting. Tap on it, and Swipe to Confirm Flash.

** If using CWM... tap on the INSTALL ZIP option, followed by CHOOSE ZIP FROM /SDCARD... tap on the folder 0/... this gives you access to the internal storage of the Nexus 7... from which you can navigate to the /download folder, where again, Chainfires UPDATE-SuperSU-v1.65.zip is awaiting. Tap on NO (the first default option) or YES - Install UPDATE-SuperSU-v1.65.zip.

On every screen in the CWM filemanager (by which you navigate) there is ALWAYS a ++++Go Back++++ option at the bottom of the screen. So you can always backout out of anything. In CWM you can also use the VOL UP and DOWN keys to scroll, with the POWER-BUTTON to select an option.

Once you have flashed Chainfire's SuperSU root package, reboot the device with the Custom Recovery's own reboot option.

Upon reboot, and whichever Custom Recovery you're using , it ***MIGHT*** suggest you are unrooted... and offer to fix root for you. Ignore it, and continue to reboot.

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And that's it... that's how you root a first generation Nexus 7 (2012).

Hope this is of use and... Good luck.

Rgrds,

Ged.