So yesterday I got in a Surface 3 which uses eMMC instead of an SSD for its memory. The device was functional, but data had been accidentally deleted. I tried a number of Linux live builds but most would hang on boot. Finally, I was able to image it using a bootable copy of Clonezilla. Here's the steps I followed to image the memory w/o having to boot up the tablet to Windows.
1. Using Lili USB creator software I set up a bootable USB thumb drive with Clonezilla.
2. With the tablet off, hold the Volume Up key and power the tablet on (this will enter UEFI) and then disable the secure boot option.
3. Turn the tablet back off by holding the power key for around 10 seconds.
4. Plug in the USB stick along with wireless keyboard/mouse dongle into USB hub, and plug hub into the tablet.
5. Hold the Volume Down button and power the tablet on (it should boot to Clonezilla)
6. Plug in destination USB drive to hub as well, and follow the Clonzilla instructions on screen.
7. Had customer log into their Microsoft account and get bitlocker key using this link (http://go.microsoft.com/fwlink/?LinkId=237614
I was quite impressed that the tablet was able to power a WD My Passport drive as well as the thumb drive and keyboard dongle for the entire 45min it took to image the whole drive, all running on battery using a non-powered hub (I tried a powered one and it was acting up for some reason). Hopefully, this will help someone else trying to get an image of the memory from one of these.