So I have a 2013 MBP that I'm trying to install to give to my friend. I've bee running a 500GB Samsung Evo 850 for a few years. I'm trying to put in a 250GB one in.
I've managed to install macOS High Sierra when in a usb cage I've got. It boots just fine off of my original SSD. So I don't think it's the cable or the ssd.
I've been installing off of a USB installer I made using my new macbook. I've reset the SMC and PRAM.
No idea what's going on. I've given up and left the 500GB drive in the computer while I keep the 250GB with my stuff on it on the side.