A:Answer I found this out the hard way as well. The specs imply that there are two AVAILABLE M.2 slots. As you found, one has the existing 256GB SSD, and the other has the WiFi/Bluetooth. I also purchase a 2nd M.2 SSD drive assuming I had another available slot. My solution was to order a PCIe to M.2 adapter (haven't received yet), but was only ~$10 - hopefully this will allow me to keep/use the new M.2 SSD drive. If not, I'll need to return and get a SATA SSD drive.
