Why is top left USB-C not working after new replacement of USB-C board

Assuming the port was working before the repair, there's really only one place anything could have gone wrong; I'd suggest you start by double-checking the plug connector from the USB-C board to the motherboard. Unplug it and examine it with a magnifying glass and a bright light; you're checking for any bent or broken pins on either side. Bent pins can sometimes be straightened with fine tip tweezers.

If everything looks good, I'd probably go ahead and pull the board back out and clean both the USB-C pins and the motherboard connector pins with 90% or higher concentration isopropyl (rubbing) alcohol. Give it a few seconds to dry then plug it back in and test.

Hopefully that's all it needs, but in case it still isn't working and you have kept the old part, I'd suggest plugging in the old board to see of that secondary port is working or not; that's really about the only way you're going to be able to tell if your new part is defective or not. If the old port works, then you've got a bad replacement.

Check all this stuff out and let us know what you find; if it still isn't working we'll go from there and figure out what to do next.