A few months back, I had a friend install rEFInd on my 2009 Mac Pro so I can use it as a server running a non-GUI version of Ubuntu. Though, after checking it a few months after it’s been off, the rEFInd boot-up manager can not find any macOS instances (only Ubuntu and some “Time Machine” drives). I tried to start the disk up into recovery mode but I got the blinking folder/question mark symbol. I cannot seem to figure out how to boot up macOS on this Mac Pro. Any help?