This guide will help you do exactly that – update your Nexus 7 (both 2012 and 2013 variants) and Nexus 10 to Android 4.4 KitKat using ADB sideload.
Before we get to the actual procedure, let's be clear that while these methods have proven to be safe time and time again, you still follow them at your own risk. We cannot be held liable for any damage to your Nexus 7 or Nexus 10 as a result of following these instructions. You've been warned.
With that out of the way, there are basically two approaches that you can adopt in this case, depending on the kind of device that you have. If you're running a Nexus 7 or 10 with root and custom recovery, you can simply use a recovery flash. For stock devices, you'll rely on ADB sideload to get Android 4.4 up and running. The requisites may or may not apply in that case.
- Stock Nexus 7 or Nexus 10 running the latest Android build of Jelly Bean 4.3 (only forstock method).
- Android USB driver for Nexus 7 / 10 installed on your PC.
- Windows-based computer with Android ADB & Fastboot configured.See guide on how to set up Android ADB and Fastboot on Windows
- Stock OTA package for Nexus 7, Nexus 7 2013 or Nexus 10
- Completely backup your Android device, check out guide on how to completely backup your Android device on PC without root access
- Rooted Nexus 7 or Nexus 10 with custom recovery. Check guide on how to root Android 4.3 on Nexus 4, 7, 10 (only for rooted method)
- Unlocked bootloader for Nexus (only for rooted method)
Procedure to Update Nexus 7 (both 2012 and 2013 variants) and Nexus 10 to Android 4.4 KitKat:
- For Rooted Devices
- With custom recovery installed, connect your device to the PC and transfer the OTA ZIP package to the root of your internal memory.
- Power off your Nexus and reboot it into recovery using Volume Up, Volume Down and power keys combo. From bootloader, you'll have to select Recovery manually.
- Navigate to Install ZIP from SD card, and then to Choose ZIP from SD card. Point to the OTA ZIP package that you put in internal memory.
- Let the flashing complete and reboot.
- That's it, you're now running Android KitKat 4.4 on your Nexus tablet. Enjoy!
- For Stock Devices
- Put the OTA ZIP package in the root of your device's internal memory, and power it off. Don't disconnect from the PC.
- Reboot into bootloader mode and then recovery as instructed above. This time you'll be in stock recovery rather than seeing a custom recovery.
- In Recovery menu, use volume keys to select "apply update from ADB" and use the power button to make the selection.
- With your device connected to your PC using USB cable, fire up a command prompt window and enter the following: adb sideload OTA_Package_Name.zip (where OTA_Package_Name has to be replaced with the actual filename)
- The update will begin flashing. Once it completes, reboot your device.