Chosen Solution
I upgraded my Mid 2012 MacBook Pro a couple years ago. removed the optical drive and put in 2 500GB SSDs and partitioned the drives so I could dual boot Mac OS and Windows 8. Recently my logic board kicked the bucket, so I ordered a replacement and put it in. Now when I boot up my Mac I get a white screen for about 30ish seconds to a minute, then it will boot into windows. Windows is fully functional but I am unable to get into OSX, I don’t remember which version I was running, maybe High Sierra. What steps should I take to try and get OSX to boot, I don’t know if there is something I need to do to this new logic board in order for my MacBook to operate how it did with the original logic board.
Are you able to make an Mac OS install on one of the drives with just one partition on it? It should be installed in the hard drive slot with the optical drive caddy removed and see if it still takes a long time to boot.
