LionChief dedicated remotes lose pairing

As a first thought, having a prolonged short is not possible without a serious event happening usually related to smoke and heat, as the expression goes. No idea what really happened.

The only times I have lost connection involved the remote being obstructed by solid structures or weak batteries.

A prolonged short, even an indefinite one, is possible.  For example, a car derails and somebody just walks away.  The LionChief "WallPack" power supply has "fold back" current limiting and protects itself by automatically lowering voltage to a safe level.  No smoke or heat.  The power supply just reduces the track voltage to zero, or near zero, and stays there until the short is resolved.

I guess I can answer my own question now.  After many back and forths with Lionel, it seems the LionChief controllers have a "sleep mode".  At first I had to get past useless information from them such as "maybe you have dirty track".

I tested the two controllers used on the layout we have at a railroad museum and, if a controller is unable to talk to an engine for 10 minutes, it will go into a "sleep mode".  When it loses contact, the controller's LED flashes quickly and brightly.  After going into "Sleep mode", the controller's LED flashes more slowly and more dimly.  I'm sure all of this is to save battery life if somebody turns off the train track power and forgets about the controller being left turned on.  That's nice, and it would have even been nicer if they mentioned it in their manual.

Lionel recommended just turning the controller power switch off and on.  We can't do that since we have the controllers captured in a way that the on/off switch is not accessible and always "on" as shown in the photo below.  (At least the on/off switch isn't easily accessible - on purpose.)

So we need to turn the 110 VAC power off to the entire layout and back on to reset.  But part of that is a 4.5 VDC supply we use to power the controllers (eliminating the need for batteries).  That power supply's output voltage decays pretty slowly (chart below shows test results) and it takes about 15 seconds to drop below 1 VDC.  So powering off long enough, and then back on, will be our solution.

I did find some other ways that sometimes worked, sometimes didn't:

   Turn the throttle.

   Press any button

   Press a button twice

All of these worked some of the time, but not all of the time.  And sometimes, none of them worked.  I find this sort of curious.  Anyway, the only reliable solution seems to be turning the power off and back on.

Install a normally closed push button switch under the table Edge in a convenient location between the power supply and the controller to act as a quick reset

That's a good suggestion.  I will consider it.  But on the other hand we have various docents who know little about running toy trains at all.  The addition of a even a little complexity can get lost along the way.  That's why just cycling the power, which they already know about since they have to turn the layout on and off generally.  (It's a wall type toggle light switch mounted at the front of the layout base) might be simplest.  If I wanted to force a time delay, I could build that in with a time delay relay.  Or I might be able to put an additional load on the 4.5 VDC supply just to help dump voltage upon power down since it has so much power to spare (it is a 1.5 amp supply which is WAY more than the controllers need).  Or perhaps put in a smaller supply which might drop voltage faster.  Or perhaps add circuitry to detect of track voltage has gone to near zero, and inhibit the controller power supply with that circumstance so that when track power is restored so is power to the controllers.  Or perhaps just make a regulator circuit to power the controllers from voltage derived from track power.  No track power, no controller voltage.  I would have to thoroughly think through any such ideas a bit.  And for ease of maintenance by museum people (should I not be around) I like to keep the system simple and use only off the shelf store bought gizmos.  But you've got me thinking about perhaps throwing something more at this annoyance beyond just "turn off for a full 15 seconds".