Greetings, access the printed circuit board, it is mounted on the blower, the blower access door is on the furnace/air handler.
Look for burn marks on the board, if you see no burn marks, look for a yellow 3 amp automotive type fuse on the board, if its blown replace it.
Beyond that you need a multi meter to measure voltage between R and C on the thermostat terminal strip on that same printed circuit board. tell me what you find, we can go from there.
So far I suspect damage to the printed circuit board or thermostat electronics
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Attach a close up photo of the wiring diagram glued to the inside of the blower access door and I will mark it up with troubleshooting instructions then follow up with step by step training and coaching until you have a solution.
Photo must be exceedingly well focused. Use the 'add files' link next to your send button to get the photo to me.
Phone call offers:
If you wish to accept the companies $25 phone call offer,if indeed they send you one, this will go a *lot faster, but it IS 100% optional... or we can continue here in this dialog box at no additional charge.