Dell XPS 13 2015 and Samsung 950 PRO m2 Upgrade

When I ordered my Dell XPS 13 back in May of this year, I ordered it with a 256 GB drive knowing I'd eventually upgrade to a 512 GB drive once the new NVMe m2 drives were out. I didn't fully grasp the variations in m2 and when I pre-ordered the 512 GB Samsung 950 PRO NVMe I expected to pop it in and go. No such luck. I should have known they wouldn't make it that easy... :-(

The drive is physically compatible of course, but has the "M" key edge connector while the drive I pulled out has the "B&M" edge key connector. I'm running the A05 BIOS on the Dell, but it can't see the 950 PRO drive a the BIOS level. The on-board testing tool reports "no hard drive". So this seems like a BIOS issue.

Anyone have any ideas? Is this a matter of Dell supporting it with a new BIOS update? Or will it never work because the XPS 13 isn't compatible with this generation of M2 drivers? Looks like I need to return this either way, but if Dell eventually supports it, I may buy it again.

If it will never work, any suggestions on a 512 GB drive that will work? Would the Samsung XP941 or XP951 work? Any idea on the difference between the two (the XP951 is $50+ more).

UPDATE: This drive is not compatible with the Dell XPS 13, and likely never will be due to power consumption (5-7 watts). You simply wouldn't want a storage device that power-hungry in your laptop. The Samsung SM951 512 GB is the best drive at the moment.