[Nexus 7 Q&A, Help & Troubleshooting] GedBlake:
Hi, hennimore...

From your post, I assume you have already CWM installed... if so, then upgrading is pretty straightforward. Assuming further, that you can boot your Nexus 7 into Android normally, you can flash an OTA .zip directly from the Nexus 7 itself... without recourse to ADB or a PC.

The first thing to do is to determine the build number of the currently installed version of Android you're running. This is found in SETTINGS>>ABOUT TABLET>>... and at the bottom, will be the build number.

Next, go

here

where you will find an archive of all currently known OTA .zips for the Nexus 7 (2012)... listed by build number.

Using Chrome (or whatever Android browser you're currently using) download to your Nexus 7, the correct OTA .zip(s) appropriate to your situation. Depending on how old your current version of Android is, you may have to download more than one.

For example... if you're currently running Jellybean 4.2.2, build JDQ39 on a WiFi only 'nakasi/grouper' Nexus 7, the 'update path' is as follows... and the OTA .zips you'll need are...

----------------------------------------------------

JWR66Y from JDQ39

Updates Jellybean 4.2.2 TO Jellybean 4.3

KOT49H from JWR66Y

Updates Jellybean 4.3 TO KitKat 4.4.2

----------------------------------------------------

Keeping in mind this is just an example (your situation maybe different), these should be flashed IN THE ORDER GIVEN ABOVE... slowly bringing your Nexus 7 up to date. From Jellybean 4.2.2 through Jellybean 4.3 and finally arriving at the latest build of Android, KOT49H - KitKat 4.4.2.

It's important you download the OTA's relevant to the type of Nexus 7 you have... so for a WiFi only model, you need 'nakasi/grouper' OTA's... if it's a WiFi/3G model, then you need 'nakasig/tilapia' OTA's.

Now to flash...

Once you've downloaded the OTA zip (or zips) to your Nexus 7... shut down the device completely. Reboot it into the bootloader, with the VOL DOWN+hold, POWER ON key press sequence. Once in the bootloader, and using the VOL BUTTONS, navigate to the RECOVERY MODE option, and press the POWER BUTTON to select. Your device should now boot into CWM.

Once there, select the INSTALL ZIP option, followed by the CHOOSE ZIP FROM /SDCARD option. Navigate (via the 0/ folder) to the /download folder on the internal storage of the Nexus 7... where you should find the OTA .zip(s) you previously downloaded via Chrome or other Android browser. Select NO, YES or GO BACK accordingly.

I'm not sure it matters, but if you have to flash more than one OTA .zip to bring your Nexus 7 up to date, then I recommend booting normally in between flashes... just to make sure everything is working OK.

Unless you're running a really old version of Android, say Jellybean 4.1.2, I can't see it taking more than a couple of reboots into CWM. And if you're currently on Jellybean 4.3, then it's just one OTA .zip flash:).

A few caveats...

If you've modified system files in any way, these OTA's will fail, as they expect to find unmodified versions of stock Android system files. If they've been changed, say as a result of a Custom ROM or Custom Kernel flash... then they can't be 'patched', ie., updated... and the OTA will abort, with no changes made.

Root and having a Custom Recovery (CWM or TWRP) installed however, won't block an OTA... although you will loose both during the OTA update procedure.

If you're familiar with fastboot, then it's relatively straightforward to re-acquire them after the OTA update(s).

Hope this helps... and good luck.

Rgrds,

Ged.