Hey pwied
Here's what worked for me. Like you, I had just purchased 2 Lenovo Ideapad 330S-15IKB laptops, and on the first one, the very first thing that it did after getting to the desktop was ask if I wanted to do the 7SCN18WW BIOS update. I did it, and after the reboot it would go to advanced recovery, or flash the Windows 10 frowny face bluescreen with an INACCESSIBLE_BOOT_DEVICE error. I couldn't find the answer anywhere online, so I started trying a few things. First, I reset the BIOS back to factory defaults, but that didn't work. Here's what I had to do to bring it back:
Step 1: Make sure it is plugged in, then get into BIOS. You can do that by shutting it completely off, then tap F2 a few times after you hit the power button
Step 2: At the BIOS info screen, move the right arrow to get to the Configuration tab, and use the down arrow to get to Storage, and hit Enter
Step 3: One more down arrow, and click enter on Intel(R) Rapid Storage Technology
Step 4: This should show the Optane volume- click enter
Step 5: You should see your Optane volume's member disks- the SATA drive and the Optane drive grouped- you need to disable the Optane volume, so click the Disable
Step 6: I did this with preserving data checked. It was a new laptop, so I didn't care about what was on it, but everything was saved. Tap the down arrow, and change Are you sure you want to disable? from No to Yes using F6 or F5, then one more down arrow, and click enter to disable the volume. It should finish in a few minutes. Then reboot
Step 7: Give it a little time- it should be super slow without the optane engaged, but it should boot from your main hard drive. From here, once you get back to your Win 10 desktop, open up your browser and do a search for SetupOptaneMemory.exe from Intel. Links will probably change, but the direct link right now is Intel Optane Setup
Select the SetupOptaneMemory.exe link for 64-bit Windows 10 (70mb).
Step 8: Run the setup- it should make you reboot, then it'll set itself up again- tell it the 16gb Optane will accelerate the 1TB SATA drive, another reboot, and you should be right back to where you were before the BIOS update.
The other laptop I had did just fine- the BIOS updated without a hitch.