I'm working on a friends Macbook Pro. It was running Mountain Lion. Hard drive will only boot into recovery mode. Disk utility reports no errors, though I still think the drive is suspect. Old computer, bought several years ago used to begin with. He has a back up, so to make it quick(ha) and easy(double ha), We decided to just do a wipe and install 10.11. Can connect to the internet in recovery mode, but online restore/install gives me and odd error along the line of ,' this operation can not complete at this time'. I had made a bootable thumb drive with the 10.11 installer on it. It wont boot and when I just try to run the installer when in recovery mode, it gives me an error saying something isn't right with the installer. OK, so I took out the drive and popped it in my Mac Pro, where it mounts. Already wiped it, should have tried this first, and thought I'll just install 10.11 on it that way. However, I upgraded to 10.12 on my Pro, so when I try to run the 10.11 installer, I get "your operating system is too new for this installer" message; I never get an option to choose a disk to install on. So how do I get 10.11, or even something older if necessary, onto this drive? We are thinking about ditching the drive and putting in a small SSD, his storage needs are small, but how do I get an OS onto the SSD if we go that route? My understanding is the Sierra wont run on his model of Macbook Pro, and that isn't a big deal to him at all, he was on Mt. Lion all of this time after all, so I don't need a Sierra hack to run on unsupported systems. TIA.