Update Android device, but not to latest version I have an Android device (Asus Nexus 7) running Android 4.4.4.  The latest version is 5.0.2.  But in order to investigate a bug report on my app, I want to update to 5.0.1.  When I select "System Updates" under Settings > About Device, I see an option to update to 5.0.2.  Is it possible for me to update to 5.0.1?  If so, how?
All you have to do is install a factory image of 5.0.1 to the Nexus before you update fully.  Head Here(all instructions are here, just posted below in case link breaks) to find the image that corresponds with your particular device.  


Download the appropriate system image for your device below, then unzip it to a safe directory.
Connect your device to your computer over USB.
Start the device in fastboot mode with one of the following methods:


Using the adb tool: With the device powered on, execute:
  "adb reboot bootloader"
  ADB Tool Download(Once installed you'll navigate to "Platform>Tools to find the adb tool
Using a key combo: Turn the device off, then turn it on and immediately hold down the relevant key combination for your device. For example, to put a Nexus 5 ("hammerhead") into fastboot mode, press and hold Volume Up + Volume Down + Power as the device begins booting up.

If necessary, unlock the device's bootloader by running:

fastboot oem unlock

The target device will show you a confirmation screen. (This erases all data on the target device.)
Open a terminal and navigate to the unzipped system image directory.
Execute the flash-all script. This script installs the necessary bootloader, baseband firmware(s), and operating system.
Once the script finishes, your device reboots. You should now lock the bootloader for security:

Start the device in fastboot mode again, as described above.
Execute:
fastboot oem lock


*Locking the bootloader does not wipe any data, but when you want to flash it again, you must run fastboot oem unlock again, which will wipe the data.