Ugh, yeah, it's what I figured.
You lost power before Windows decided to actually write the files Demon told it write, so there's nothing in them. You can see this for yourself by opening Tower_16_Data.xml and Tower_16_Data.xml.bak. If you open them in Notepad++, you'll just see the NUL character over and over, whereas opening Tower_15_Data.xml will show a variety of characters (jumbled in appearance due to how I format things, but obviously some kind of data as opposed to just the null character over and over.)
Your current party and its data are stored as part of the floor you're on, so if that file gets toasted, there's not anything left for me to work with restoring things.
All I can do is offer my deepest apologies, and reiterate that I will take another swing at this after the 3/1 release. But, as I said before, practically any program that stores data on your computer can lose that data if your computer loses power at certain times, so I'm not sure I will be able to assure a 100% success rate here. I will try to improve the odds again though.