I have a perfect working macOS Sierra. Volume named Macintosh HD. Mac keeps booting to a screen that says install mavericks. I click startup disk. It doesn't recognize any. In disk utility. It is there. Macintosh HD. Verifys just fine. Something is forcing my mac to install mavericks even though I have a perfect running copy of sierra. I reset the pram. Same thing. Install mavericks it says. I click startup disk. It doesn't recognize Macintosh HD as being a valid 10.12.1 disk. Like it needs to be blessed.