Disclaimer: Instruction here requires advanced knowledge of Android systems. Any mistake can render your Nook useless, and I takes no responsibility when that happens. You are on your own and you are warned.
I have 16GB Nook Tablet and wish the media partition can be much bigger for my own personal audio and video. And found that there are tools and tutorials available but they are scattered so I have it organized here.
You need two microSD cards. One must be bigger than 2GB (Note: some 2GB card is not big enough so your best bet is to get a 4GB card) and all data on that card will be erased. Let’s call it boot card. Download the bootable Jellybean (Android 4.2.2) SD card image from here. Unzip it and use Win32 Image Writer to write it to your boot card.
Another microSD card should be big enough to backup all your data. Let’s call it backup card.
Boot Nook Tablet into Recovery Mode
Insert boot card into Nook Tablet and restart it. Hold n button when you see prompt of “Hold n for menu” at the lower part of the screen. Release it when you see “Boot Menu” shown in the middle of screen. Use volume up/down button to select SDC Recovery and press n button to start recovery.
Remove the boot card and insert your backup card. Follow the instructions on the CMW recovery utility to backup your nook. When backup is finished, remove the backup card.
Run Nook Tablet in Debug Mode
Insert the boot card to Nook Tablet and restart it. The Nook Tablet will boot into Jellybean (Android 4.2.2). Go to Settings->About tablet, tap the build number many times until you see “Developer mode is enabled”. Back to settings and now you can access Developer options. Enable Android debugging.
Start SDK Manager and install Android SDK Platform-tools. It will by default select latest Android version but you don’t have to install that for this purpose.
Install ADB Driver
Download the USB driver for Nook, connect the nook to computer with USB cable. You’ll get the message that driver is not found. Manually install the downloaded driver, select the Composite ADB driver.
Follow the instructions here to start ADB tool. Make sure that you can run “adb devices” to see your device. If your device is offline, check your Nook, if you see a prompt for permission, please allow the computer to connect.
Make sure you can run “adb shell”
Follow the instructions in the post below:
Use boot card to boot into recovery mode again. Then replace it with backup card and restore your Nook Table. Once restoring is finished, reboot your Nook and your mission is accomplished.