Just got an inexpensive refurbed Laptop from Woot. Booted it up to get a PXE-E61 error.
Looked at the BIOS - the boot order was all wrong, they had Network Adapter at the top of the list and HDD at the bottom. I updated it to 1-Optical 2-HDD 3-USB 4-Network, saved my changes + reboot to try to recreate the error - and it works fine. Right into Windows, which updates itself and boots a couple of times. I shut it down, thinking everything is good.
Next day, I power it on, and I get a HDD fail message. I boot into BIOS, which reports it can see the HDD. Do a SMART scan - pass. Do a Quick test - pass. Decide to skip the Comprehensive 3-hr test and reboot. Works fine. I download WD's Win-10 Disk Check Utility and let it run.... no problems.
Restart - works okay.
Power off / Power on - can't see the HDD.
I check the BIOS version - it's old and there's a recent update available, so I flash that. Get that done, reapply power, HDD works. Power off/power on - can't see the HDD.
I pull the HDD and put it in a USB dock, allowing a different machine to scan it - works fine. So I'm pretty much convinced that the HDD is okay.
The HDD "disappears" ONLY when I'm bringing the Laptop up from a Powered Off state - and when I do that it only happens about half the time. It never happens when I'm rebooting after a successful Power On. When it sees the HDD, everything is great. So I'm thinking it's probably something simple, like the SATA cable, though looking at the innards I'll be darned if I know how to dig that out to replace it.
The Laptop only cost me ~$300 and I can return it for a full refund. Woot has also offered me a partial refund of $30 if I want to keep it and get it fixed locally. I've got 30 days, not sure which way I should lean on this.