XPS 8920 will not reboot from SSD

when I see those msg  "Start Up Repair" I always sense it is Microsoft's feeble attempt to appear to be omnipotent but it has never worked. I like Windows 10 but it has flaws. In your case, perhaps easier to fix the issue than trying to understand what caused it.  It could be some files got corrupted on your ssd which compromises the boot.  Always back up important file on ssd elsewhere because when it works it is super fast but when it dies it gives no warning and goes away like a puff.  If possible back up your files now and do a clean install of Windows 10 on the ssd in UEFI mode of bios.

At an administrative command prompt try 'sfc /scannow'. Also you could try 'DISM /Online /Cleanup-Image /RestoreHealth'.

@Vic384  - Running those commands won't help because PC boots OK from the original HDD which has it's own OS install on it. Sounds like the OS install on the SSD needs to be repaired, assuming the SSD just hasn't failed...

@ChuckFTL  -  If you can connect the SSD as a secondary drive and boot from the old HDD, back up your personal files that are on the SSD before doing anything else. Then download/install Crystal Disk Info on the HDD and use CDI to test the SSD.

You never mentioned the version of Windows. Assuming it's Win 10, do you know if Windows Update recently installed the KB4549951 update? It's causing all kinds of problems and will have to be removed.

Assuming the SSD hasn't failed, download the Win 10 ISO for free and follow Microsoft's instructions at that site to create a bootable USB stick. With PC off, SSD connected as boot drive, plug the USB stick into PC. Then power on and start tapping F12. When the F12 menu opens, look for option to boot from USB.

When the Win 10 installer loads look for and follow the prompts to run a repair on the SSD.

@RoHe I made the suggestion because the OP mentioned using the Command Prompt to see the files on the SSD. I assumed the OP got the Command Prompt from the SSD because he did not mention the original HDD until the second paragraph. If the OP had booted from the original HDD he could have used File Explorer the look at the SSD, he didn't need to use the Command Prompt. The fact that the OP may have gotten the Command Prompt from the original HDD did cross my mind, but he never mentioned that in his first paragraph, so I assume somehow he got to a Command Prompt from the 'Troubleshoot' option.

Hi Ron –

Thanks for the reply and suggestion. Here’s what I have done:

1. Cloned my SSD to an HDD so I now have a complete backup of my data on the SSD.
2. Downloaded the Windows 10 ISO to a USB. Disconnected all HDD and USB devices on the failed computer so that only the M.2 SSD is active.
3. Booted from the USB on the failed computer. I chose the option to "Repair your computer" as you suggested, which gave me a screen with “Troubleshoot”. After selecting “Troubleshoot”, I selected “Repair Startup”. The screen changed to “Analyzing your computer”, then “Attempting Repairs”, then went blank, and then the computer rebooted, which failed because it tried to reboot from the SSD (not the USB).
4. I tried to reboot the Windows 10 ISO USB again, but this time, I got a message saying that the computer needed to be repaired. I tried again, but now I am unable to boot from USB. I also got this message: File: \windows\system32\winload.exe error code 0xC00000e. The file is missing or corrupted.
5. I rebooted with my old HDD so I could look at the SSD and there is a winload.exe file with a date of 4/16/20 and a filesize of 1478KB. This date is before the original failure, which happened just a couple of days ago.
6. I recreated the USB on my working computer with the Windows 10 ISO and was able to boot again and am back to the “Troubleshoot” screen. In addition to the “Repair Startup”, there are other options, including a “Command Prompt”.
7. I don’t know if the \windows\system32\winload.exe error is meaningful or not, since it only happens when rebooting from the USB. I did some internet searches and one suggested rebuilding with BCD. But, I didn’t want to attempt further until I heard from you.

Thanks again!

Hi -

When I try to boot the computer, the blue screen with Troublshoot has sever options, including "Command Prompt", which is what I initially used to look at files. It was only later that I realized that I had the original HDD which I could install and would boot and give me the File Explorer.

I did try the sfc /scannow but it didn't find any errors. I couldn't get the DISM command to work - it complained something about not being able to use this command in WINRE (or something like that).

Thanks for your suggestions!

Re: 

1. Cloned my SSD to an HDD so I now have a complete backup of my data on the SSD.
2. Downloaded the Windows 10 ISO to a USB. Disconnected all HDD and USB devices on the failed computer so that only the M.2 SSD is active.
3. Booted from the USB on the failed computer. I chose the option to ...

If you chose the option to clean install of Win 10 instead of repair, wouldn’t that be much easier?  
Clean install: advanced drive option>delete all partitions, create new partition, format, continue

You could try repairing the Master Boot Record from the Command Prompt. https://pureinfotech.com/repair-master-boot-record-mbr-windows-10/

@ChuckFTL   - Did you install/run Crystal Disk Info from the HDD with SSD installed as a secondary drive to see if the SSD still "healthy"? You'll be spinning a lot of wheels if the SSD failed...

BTW: What size USB stick did you use for the Win 10 ISO? MS says to use an 8GB stick, but many users find that at least a 16 or 32GB  stick is necessary.

@RoHe- Yes, Crystal Disk Info says the SSD status is GOOD - 97%

Also, after I cloned the SSD to HDD, I tried to boot from that HDD and got the same failure - blue screen with "Troubleshoot".

The USB stick I used was a brand new 32GB stick.

chuck

@RuskinFThanks for the suggestion. Turned out not to be the C drive. I recreated the EFI partition (boot) and the computer is working again.

Looks like your C: drive got corrupted.

Do a clean install of Windows and go back to using your system as you used to earlier.