My 13.5" Surface Book 2 that I bought in January had the same problem: it wouldn't wake up sometimes unless I detached the screen, and only then could I power it back on.
In April I made an appointment at the MS store, about 30 miles away. They said it was defective and replaced it on the spot. I was in & out within 20 minutes.
In July, the replacement started doing exactly the same thing.
I'll try the hibernation/sleep fix and note if it works. However, since BOTH new Surface Book 2's had the exact same problem a couple months after they began being used, it seems there's a defect that MS needs to fix.
If a end up getting a third Surface Book 2 and it fails the same way, I'm wondering if I can simply get a refund.