Before I go on to get a quote by a professional, I was wondering if there was anything I can do myself to fix this problem:
I have a Rheem Imperial (1990s model) furnace and today, it stopped working. I figured it might have been the thermostat since it was pretty flaky so I replaced it. After doing so it, still did not work. So I went to the furnace and looked at possible problems. One thing I noticed was there's a power switch which I was able to turn on/off prior to this event. Today, I tried to turn it off, it flipped back on. This power switch is directly next to the furnace and feeds into the furnace from the breaker box.