To test the suppressor is quite simple as if you have a test meter you need to remove the top and you will see the mains suppressor. You will see 2 live wires and 2 neutral. Make sure its unplugged and test for continuity between the 2 live wires and the same on the neutral and you should have continuity between them both. If one doesn't then the suppressor is the fault.
But to be honest its quite rare these fail. If the power supply is fine its a good chance it may be the control board itself.
Once you have the top off you will see the control board attached to the side on the right hand side.
Take this off and see if theres any signs or it blowing on there.
But you can test the suppressor as above to see if that's ok or not.