Mine will boot with the typecover on, but it takes several minutes to do so. For those several minutes it will stay on the Windows splash screen without the spinning dots. Without the cover attached it boots in about 15-20 seconds.
I did take mine to the MS store on Tuesday thinking maybe it was just my device, but every demo model they tested their with different combinations of the new type covers (fingerprint and non-fingerprint) exhibited the same problem. Works fine if you attach an older typecover instead.