No boot from internal HD nor SSD, but via USB.
My MBP stopped booting out of nowhere. I thought it might be the hard drive, and I wanted to change the internal HDD to SSD anyway, so I bought a new SSD and put it inside, but still no chance.
I put the old HDD into a case and connected it to another mac: Seemed okay, I could read all my data and made another backup.
I changed the drives again in order to format the old HDD and clean-install MacOS. Installation seemed to work for ~2h but then just stopped without any message (tried several times).
Then I tried to boot from the new SSD externally, connected via USB. This worked, I installed El Capitan and I am still using it right now.
The crazy thing is: While running on the external SSD I can read my data on the old HDD (internal), so it can't be Logic Board nor SATA cable, can it?
Any ideas what the problem might be & how to solve it?
Thanks a lot in advance!
Is this a good question?