By the term "short", do you mean it is blowing a fuse?
If you mean some tester is showing a "short", it is all to common to get a false reading. Any digital voltmeter can trick you as well.
I was giving my brother a class on voltmeters, Amps, test lights, and analog meters. It was perfect. One of my meters had an "intermittent" battery connection which allowed me to demonstrate how to get confidence that your meter is not lying to you.
I'm digressing but as mentioned these things are almost bullet proof. The real amp is in the head of the antenna and yes those can give some grief.
You can't just bypass the box because it routes DC to the antenna head when activated.
Take your time and take pictures,
