Chosen Solution
I bought a new hard drive to install Sierra but when I plug it and try to erase and format it through disk utility it gives error and fails to format to journal. however when I plug the hard drive via external via USB connection I’m able to format and complete the whole installation. Is it because it cant detect SATA drivers on the board since its new? Update (10/09/2017) The MacBook Pro “Core i5” 2.5 13-Inch (Mid-2012/USB 3.0) Hard drive is Toshiba 500 GB I’m currently using it now via a USB external connection with MacOS Sierra installed on it.
What was happening with the old hard drive. The most common issue on this machine (if it is the non=retina is the hard drive/IR cable. Apple was even replacing these for free for a while. MacBook Pro 13" Unibody Mid 2012 Hard Drive Cable Replacement
