The major problem with Brake Buddy, Even brake and the other "Box in the driver's seat" systems is that though they advertise "no installation" this is simply not true. You must INSTALL it every time you hook up.
This leads to two problems. As the O/P found out the hard way (As Did I with a different system) Every install is a chance to GOOF and cause a problem
And 2nd. With the "Box in the seat" jobs. For a short tow the tendency to say "oh, That's too much trouble" and regret it later.
I'd get the Ready Brake re-installed, and I'd personally inspect the job to make sure it's done right.
One warning on that system. If you live in the great salted North it can rust and bind.. Just exactly like your parking brake cable does (Same type of cable in fact) Assorted ways to keep that from happening.
