My 2-hour old 7940 just did this basically.

It passed one final radio test before firing.

Engine fired for about 2-seconds and the servo snatched WOT full-throw limit of the servo (beyond the EPA setpoint). I happened to catch the engine before it revved away too far; but she still wrapped hard and fast.

Now as soon as it has voltage it goes full-throw.

I reversed the channel in the radio and it does the same action in the reverse direction. Makes no attempt at centering or following any commands.

Hopefully Hitec follows through, but it seems they're having an abnormal number of servo failures lately with the digital family.