Can’t reinstall macOS to upgraded SSD

So I was gifted an old Mid 2010 MacBook Pro that at this point, I’m ready to just give up on. I purchased a Samsung 970 Evo 2.5 in. SATA SSD (250GB) and could not reinstall macOS no matter what I tried. I tried Internet Recovery, I tried using a USB installer and I continuously get the “prohibitory symbol” when it’s near completion of being installed. I’ve tried on both WiFi and Ethernet, same results. However, I can reinstall macOS if I throw in the original HDD but for obvious reasons. So I figured, let me see if the SSD is the issue and so I purchased a SATA to USB Cable and was able to successfully reinstall macOS onto that externally. Then I came across a thread on here that suggested upgrading the internal Hard Drive Cable, which I purchased and arrived today. I successfully installed it and once again tried to reinstall macOS to only get the same issue again! I can install macOS to the SSD if connected externally and can install it internally and it boot up fine but if I restart the computer it will boot to the “prohibitory symbol” It’s like it doesn’t like the SSD installed internally but will accept it externally? I don’t know what to do at this point. Anyone have suggestions or ideas? I’m beyond frustrated and usually can figure out these sort of things on my own but figured I would reach out for help on here. Thanks in advance to anyone who responds to this lengthy post.