How do I boot into Test Mode?

NOTE: This project is deprecated and no longer actively maintained as of 1st July 2019. More information about the deprecation can be found here.

To boot into Test Mode, several steps have to be executed.

1. First, open Windows Update and let it search for updates. Install all the available updates. You have to do this to stay protected.

NOTE: If Windows Update takes forever to search for updates, go here and follow the guide. Remember to stop the Windows Update service first before you install an update manually (Windows + R --> services.msc --> Windows Update)!

NOTE: Alternate fix for a stuck Windows Update.

2. Now download the latest version of the Development Tool.

NOTE: You can find it here.

3. Extract Windows_RT_8.1_Development_Tool_VX.X_BUILD_XXXX.zip. You will find a folder called Windows_RT_8.1_Development_Tool_VX.X_BUILD_XXXX. Inside the folder, you will find a file named Windows_RT_8.1_Development_Tool_VX.X_BUILD_XXXX.bat. Run Windows_RT_8.1_Development_Tool_VX.X_BUILD_XXXX.bat.
4. When the tool asks for administrator elevation, click yes.
5. If you understand and accept the disclaimer, press any key to continue. You will see a menu.

1 = Modify Windows Update

2 = Remove Infected Updates

3 = Boot Into Test Mode

4 = Boot Into Normal Mode

5 = Exit

6. Now Windows Update needs to be silenced because Windows Update delivers updates that infect Test Mode. Choose option 1. You will see another menu.

1 = Block Windows Update

2 = Let Windows Update notify you before downloading updates.

3 = Let Windows Update automatically download updates and notify you when it is ready for installation.

4 = Let Windows Update automatically install updates.

7. Block Windows Update by choosing option 1. After you have chosen an option, press any key to return to the main menu.
8. Now you have to remove the updates that infect Test Mode. Choose option 2 in the main menu. After the tool has removed the infected updates, Windows RT 8.1 will automatically reboot.
9. After the reboot, run Windows_RT_8.1_Development_Tool_VX.X_BUILD_XXXX.bat again (You may have to run it multiple times)
10. Choose option 3 to boot into Test Mode. Windows RT 8.1 will automatically reboot again.
11. After the second reboot, you will have to check if you have successfully been booted into Test Mode. You have successfully been booted into Test Mode when you see a watermark in the right corner of your desktop. If you don’t see anything, try the possible solutions given beneath. If you still don’t see anything, please reply here.

Solution 1: Run the Remove Infected Updates script two or three more times.

Solution 2: Go to Control Panel --> System and Security --> Windows Update --> Installed Updates. Remove the Infected Updates (listed on http://www.technique.cz/storage/JailbreakDisablerUpdates.jpg) manually.

Solution 3: First follow the instructions posted on https://forum.xda-developers.com/showpost.php?p=75389310&postcount=556 and then boot into Test Mode.