On Thu, 21 Jan 2016 14:26:20 -0600, dpb wrote:

I hadn't seen the thread but sounds to me like perhaps you didn't
actually reset it before trying to turn it back on...most (all?) require
a manual "push _fully_ off" to reset after a trip; if you don't they're
not reset.

I'm guessing this time your movement did include enough in the "off"
direction to do the reset

It constantly wouldn't set.

I flipped that circuit breaker scores of times from fully off to fully
on (I have a lot of experience with circuit breakers, just like anyone
here would - even if I've only replaced one in my entire life).

I can only think of three scenarios that make sense because the short
was not momentary. It lasted for hours two days ago.

At the time I was actively flipping the breaker, so, it wasn't a
*momentary* short (the only thing I could find wrong was one bad
bulb in a set of five in a ceiling lamp).