What is the test mode?
The test mode message indicates that the test signing mode of the operating system is started on the computer. The test signing mode may start if an installed program is in a test phase because it uses drivers that are not digitally signed by Microsoft.
The solution is short and simple.To disable it open Powershell or CMD ran as administrator and type the command:
bcdedit -set TESTSIGNING OFF
After the command was completed,restart the computer.