What is macropad? Where did you get the hex file from? What is QMK? Provide links to the stuff that you have used.
How did you flash the hex file? Via USB or via ICSP?
If the latter, you will probably need to burn the original boot loader.
What happens in Windows device manager when you reset the connected board? Does it show a port with "boot loader" in the title?
What you can try
1)
Select the com port in the IDE while you can; it does not matter which port you select. If you have another Arduino or so, connect it and use that port.
2)
In file -> preferences in the IDE, enable verbose output during upload.
3)
Connect the ProMicro while keeping it in reset.
4)
With ProMicro still in reset, compile and upload.
5)
When the IDE reports the memory usage and starts spitting out line like {COM x, COM y} => {}, release the reset button.