You don’t necessarily need the GCU to restart the Ignition service. If you are comfortable with the command line, you can also open a command window and type in these commands:
net stop ignitionnet start ignitionThat being said, the GCU should still open without issues. Which version of Ignition are you using? Another thing to try is to open a command window, navigate to the Ignition installation folder and run:
launch-gcu.bat and see if any errors come out.