I noticed that the SATA drive was missing from File Explorer.  I then disconnected that drive, and the computer quickly booted.  SATA is set for RAID. The SATA drive has data files and is partitioned. How should I troubleshoot the SATA drive? OK, glad you discovered the 'root' problem. Now what to do it the next question! So, with that in mind, I have to ask: You can change the setting, see here, for instance, [URL]  but I STRONGLY suggest you MAKE a back-up of the SSD (if still on RAID setting in BIOS). Some times you might lose the drive contents. Back to the hard drive though, you might not be able to recover anything. Right now, I'd go out and by another drive and put it in. IF you had a back up of the old drive and its partitions, you CAN restore it. I learned my LESSON a long time ago... I make BACKUP using the 'old' Acronis True Image (I said OLD because they changed to subscriptions and added features I do not need) weekly of ALL drives on my PC and the same on my wife's. Macrium Reflect is another suggested (Free) but that will end soon I recall, but here is a link, [URL] (NOTE: you will need a drive you can put the back up on, so if the existing hard drive can't be recovered to be usable, buy a new one or get a USB External drive). Assuming you can't access the hard drive at all, I'd suggest Googling "recover a hard drive" and look at the links. There are programs, both free and fee that might work (I guess depending on the reason the drive doesn't work)? However, if the electronic are fried, nothing short of a company that recovers the drive by physically removes the platter(s) and uses tools to read it. I wish you luck, but it 'sounds' like complete drive failure somehow? If not, could still be a cable or motherboard controller problem (I doubt it) and getting a new drive and it too can't be read/used would point to that (and the cable is the easy fix and power connector too). Assuming it isn't the simple fix, DATA and POWER cable (check those again, disconnect and reconnect, and the data cable from the motherboard as well), no way out but a new drive I guess? Next thing I'd do, also buy a USB External drive and the 'real' Macrium (or other back up program) and start making backups ROUTINELY. I do it once a week (I can affordup to lose one weeks data loss) but you can do it as often as you wish, and decide on type of back ups. Need to know more or have questions, Private Message me rather than here.
I have a little used 2 year old XPS 8940. Over the last several months, it has taken longer and longer to boot to Windows 10.  Now it can take a couple of hours, if it even gets there. Once it does boot to Windows, it seems to run fine.   Just to enter the bios through F12 can take an hour, if it gets there. And, to do one of the F12 processes available, can take an hour or more. The Dell diagnostics function says the computer/memory is fine.  When the computer did boot to Windows, I did some troubleshooting like running scandisk and adjusting what opens on startup.  Not sure what to try now? Thanks in advance.
XPS 8940, won't boot