Anika the Aardvark

I'm doing command-R to get into recovery mode and it's taking me into windows recovery mode HOW AM I SUPPOSED TO REINSTALL MAC OS FROM WINDOWS

it's too old to have internet recovery, apparently, which means all it has is the built-in recovery, which is stored on the hard drive. the hard drive I just replaced. So I guess the answer is "burn a USB/DVD installer, and boot from that"

so it turns out the way you make a USB installer for El Capitan is to download the disk image, which contains a package, which contains the app, which contains a command line tool to write out the USB image, right?

here's the problem: the package is an installer, which installs the app that'll install El Capitan. In other words, you have to be running it on a computer that is compatible with El Capitan

so if you have two macs: a broken one that maxes out at el capitan, and one that has a minimum OS later than el capitan you can't use the latter one to fix the former one

I got an installer from a slightly-questionable source, used an third-party app to convert the installer into a USB drive, and only THEN realized I accidentally selected 10.13 instead of 10.11. 10.13 won't run on this laptop