Please follow these steps to disable test-signing mode:
Click Start, and then type cmd in the Search box. Under Programs, right-click cmd.exe, and then click Run as administrator.
At the command prompt, type the following text, and then press Enter:bcdedit /set TESTSIGNING OFF
Then type the following text, and then press Enter:bcdedit.exe /set nointegritychecks off
Restart the computer.