It was the second flight of the day. I actually turned the RPMs down last week, and haven't touched the settings since. When I plugged the battery in for the second flight I heard a snap and saw smoke from the ESC. I immediately unplugged the battery and put it in the shade for about 20 minutes. Then I plugged it into my charger and it showed 100% on all three cells. It took about 10 minutes at 0.5A for all three green lights to come on, indicating full charge.
I don't think I can ask Brodak to replace it. When I got home I unhooked everything and took the ESC off, hooked the power leads to a 12V lead acid battery, and the rest of the smoke came out. Then I took it apart as much as I could (without using a hammer) and found a small burnt pinhole near the center of both front and back circuit boards.
Obviously one of the components failed. Not being an electronic wizard, that's all I can say with any confidence.