Why is boot device (256GB stock) not found then found again

After device turned off, upon turning it on again, no boot device found. Sys config, boot from device, boot from file, steamOS recovery stick, and windows installer (adv install disk selection section) could not find the ssd. But, after approx an hour or more, it boots up fine, ran some games, then after turning it off, boot device not found again and the wait begins again. Is this a software/hardware issue? Also, wake from sleep is just a black screen and a frozen screen on desktop mode.