I don't know if replacing the control board with a different unit model is compatible. So I'm not sure if the logs are right after you switch to the 1246 control board.

About the FMS tool, there is another version of this tool that has an aging button you need to download it again here https://canaan.io/service/447 make sure to download the FMS app or tool the 2nd or the 3rd one has an aging button near diagnose button.
Some people solve their case by using the aging button it is just a calibration and let's hope that it will work if not try to run the miner with one hash board test them one by one and let's see if maybe one of the hashboard has a short circuit that leads to other components not work properly. Remove it once you find the culprit.