Ubuntu 16.04/Win 10 Dual Boot install: Cannot reduce partition below 50% in Windows, Ubuntu does not detect drive

The answer to this scenario was to (sorry #'d steps causes spam error?):

• Reset BIOS from AHCI problem by disconnecting battery as @oldfred mentioned. Search "dell 9350 service manual" -can't post link due to low rep :() ; note that there are clips attaching the case, and also the screw in the middle by service tag. Disconnect both CMOS and main battery, then power cycle. This resets bios.

SEGWAY - use Windows to download windows 10 USB installer via (https://www.microsoft.com/en-us/software-download/windows10ISO). A RECOVERY USB will not work in my experience - it will only reinstall windows without letting you determine partition size!

Go to Dell's site and d/l the wireless drivers. They won't come with the new windows install. http://www.dell.com/support/home/us/en/19/product-support/product/xps-13-9350-laptop/drivers

• Turn off secure boot, and switch to AHCI in BIOS settings (this is via f12 during boot on my 9350 system). I don't know why the secure boot is an issue (as it's supposed to work), but it is, for me at least.

• Boot live usb, run gparted, destroy main windows partition (Keep in mind this is only necessary if you desire a hard drive setup that is less than 50% windows - windows itself will not let you resize the partition to less than this in my experience).

• Shut down, then insert your aforementioned windows 10 install media, install new windows, which will let you pick your partition size (tho' this may work without step using ubuntu to destroy the original, this is how I did it). I picked 70GB, since I am keeping it only to update bios or for emergencies (VM otherwise is better, I think). Stated minimum is 20GB, but already I am seeing 21GB taken by the system, so keep that in mind.

• Finish install, then use those dell drivers I mentioned to get your wireless back. Run all your updates, set it up as you want, yak yak yak.

• Shut down, go back to live Ubuntu USB, and install Ubuntu in remaining space (~375GB on this system)!

• You'll likely want to scale the display for QHD, do this in display settings (hit windows key, type display).

• Enjoy your clean ubuntu/windows 10 dual boot on the dell 9350! So far I have no significant odd issues on 16.04 LTS - the touch seems to not work when coming from suspend (I think), but that's for another post. Everything else is great - go for it!

Thanks for all the help AskUbuntuers!