I had an old computer in storage for a couple of years. Separate from its disk drive (SSD). After I reinstalled the drive, it would not show many signs of life. Not even a POST screen. I plugged and unplugged everything from the motherboard (except the processor). Then it would limpingly sort-of boot. The problem looked like disk errors. I tested power-supply voltages with a cheap tester designed for that purpose. OK. I tested the SSD on another machine using a SATA to USB 3 dock. The disk looked OK and I was able to fsck the appropriate partitions. Still booting was a bit wonky. I replaced the SATA cable for the drive. It booted fine. ==== The system is quite old. It seems to have some oddball limitations on booting: - no UEFI support - the firmware cannot boot from a Fedora 29 Live USB stick. It can be selected as a boot source, but the boot doesn't happen - but two OSes (CentOS 5.11 and Fedora 20) do see the USB stick and contents - the firmware cannot boot from the SATA Bluray / DVD / CD drive. Probably the firmware can only boot from ATAPI optical drives. - Fedora sees exactly the expected bytes when it reads from the SATA optical drive (the contents are the Fedora 29 Live image)