Trying to find some common ground here so we can figure out if it's a hardware thing or a software thing...
I can confirm the Dec 10 update did not fix my issue. Just 10 minutes ago, I picked up my Surface 2 from my desk, flipped open the Type cover and the Surface is nonresponsive. I could feel feedback once I pressed the windows key at the bottom of the screen but couldn't get the device to "wake up"... I removed and then re-attached the cover... No Response. I held the power button several times ford about 15 to 20 seconds but no response.... I plugged in the device to the charger... No response....
Finally I was able to get the device to reboot by holding the power butting at the top.. The device rebooted and has about 95% power...... This is starting to become an issue. I've had this issue of trying to get my "wake up" in the past at customer meetings...........This needs to be fixed or I'm going to need to look to another product to suit my needs, For all the short comings of the Surface 2, the basic ability to "wake up" reliably is pretty high on my list......
I'm having this issue on my 2520 as well. It gets difficult to show a device off when it won't power on.
I talked with Nokia Support the other day about a separate issue and asked about this. The agent confirmed that it is a known issue and that a team is working on a fix.