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Have you checked for a blown fuse on the control board?
Does the furnace have incoming power as measured with a voltmeter? 120 volts?
If not, need you to take a couple measurements and get back to me. Get a voltmeter, set to "volts AC" and measure incoming voltage (120 volts) and also take a measurement across C or COM to R at the board. We should have 24 volts there. If you can upload a clear picture of the wiring diagram, this will help me tremendously.
Did you see my last post?
If no voltage across C or COM to R, then it would be a burned out transformer.
It would be the thermostat one.
You can also take the thermostat off the wall and measure across R to any other terminal. You should have 24 volts.
RC-RH should be tied together. You can measure from either one of those to any other terminal.
OK, that would be a bad transformer, then, if furnace has power. You will probably need to purchase part online as local dealers may not sell to you unless you're a contractor. Found this site that sells Thermal Zone parts. You can probably call, give them your model number, and they can locate that transformer for you.
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Nope, not if you have no low voltage. You need to have 24 volts available for the control circuit. You said you have nothing across C or COM to R at the board. You could tip the board over, and examine the back to see if there are any burned or scorched areas.