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Hello, tell me in detail what happened, if you got sparks, look on the printed circuit board for a 3 amp automotive type fuse that may have blown.
We can go from there
I need the model number of the thermostat, most of those can be programmed internally to reverse the function of the O/B terminal and solve the problem you are having... look for it in the installation manual under advanced settings or set up settings.
So far it sounds like you may have wired it correctly and just need to reverse the OB terminal function... see if you can find it in the manual, meanwhile I will be looking for those instructions myself
If you can send me a photo of the thermostat wire connections at the thermostat and where those very same wires connect to the printed circuit board inside the furnace that will help a lot
I am here but it takes time to type responses, sometimes longer to do research, a 15 minute delay is not uncommon.
Use the paper clip icon at the right end of your tool bar to attach the pictures.. they need to be well lit and very well focused, the printed circuit board is in the blower compartment on the furnace.