I have pretty much exactly the same problem... I received the XB10, got it out, charged the battery, put batteries in the transmitter, and fired it up... it worked perfectly. Put it in the box, wrapped it, moved it only once, very gently, got it out on Christmas, and it didn't work. Just beeping from the car (and the ESC flashes).

I noticed the same behavior when I had the transmitter off when I first got it... but no idea what could be going on.