Trailing F3 lost it?

Sounds like you may have taken out one of the drivers.  Does it start running immediately when you apply track power before you command movement?

Mr Muffin's Trains,

   Real bummer, this is not the 1st ABA unit I have heard this happening to, I believe gunrunner john is corrrect, I know this is a little late, but the Scott 10 Amp breakers

would have saved you a lot of problems, you might consider putting them in so this never happens again, the 10 Amp breakers are real sensitive and your short would have popped them, and saved the trailing unit.  Man I hate to see this, that is for sure.

PCRR/Dave

Certainly worth a shot, I'd also consider resetting to factory defaults and adding again.  The description doesn't sound like this is the issue, but you never know.

Put the slave on the track by itself (no tether to main).  Apply power.  If it starts moving by itself you know for sure you have a slave problem - probably a stuck-on electronic component on the circuit board. 

If it doesn't move you may still have a slave unit problem but this provides an additional data point...

Ditto what Stan says.  Slave on track by itself should stay dark and motionless.  This is repairable at the component level in most cases.  I can do this if you need assistance.  E-mail is in my profile.  G

Thanks all…. he took the units home but I will see if I can get him to bring them back and try this out.