OK, as I mentioned, I have a mid-2009 polycarbonate MacBook, that I put a 256 GB solid state drive in and installed macOS Sierra on. But when I recently reset the PRAM, whenever the Mac boots up now, it shows the message that SIP has been enabled! I am unable to do certain things like change the brightness of my display. I try to boot into Recovery Mode to disable it, but I can't get into Terminal! The menu bar doesn't work at all, except the wi-fi icon. I think this is another thing SIP is causing, thus making it almost impossible to disable it in the first place! Can anyone give me any help on what to do here?