I'm trying to help a friend with his c55 laptop. It's practically brand new--he brother used it a few times then put it back in the box and stuck in a closet (2016). It was working fine then.The brother gave it to my friend--he tried to boot it up and got the "no bootable device--please restart system" message. Through F2 I got him into thje BIOS>disable secure boot>UEFI>HDD as number one on the boot list. Same message. He made sure the hard drive was seated properly. Same. I got him to do CHKDSK /f--no problems detected. I had him change out the hard drive for a spare he had that he knows is working--same message.