I have a Goodman GMP furnace which now will not come on. When I unplug the unit and plug it back in, it tries to start for a split second and then just quietly hums. Any thoughts?

It sounds like the motor is seized up but you cannot know until you open it up and use a meter to find out what the problem is. You have to use a meter to check out a furnace; guessing does no good. DrTom4444