My parents old computer stopped booting, quickly going to only showing a black screen when the power button was pressed (fans would spin, but no signal after the BIOS). When I put the old hard drive (Seagate Barracude 1TB 7200) into the new system (windows was installed on 240GB WD SSD) the same issue persisted. Connecting the old hard drive into my own computer, I was able to stop the old HDD from being the primary drive, and boot into windows. It still shows up in the BIOS but not anywhere in Windows (including disk manager, the seagate tool and CrystalDiskInfo). The old system was a prebuilt, and every time I boot the computer it is set as the primary drive, which I have to change or the original problem persists. There is data to back up from the old HDD, what is the best way to do this?