Apparently, the charging issue was the culprit. After waiting 4 days for the unit to completely drain, I connected it back up to the charger, and vióla, the unit once again had a display, and commenced charging. Woo! I had it up and ready for the Soccer Parent 5M run on Friday evening with Evan (route). The route incorporates a part of the Escape From Prison Hill trails to and from Edmonds fields. Relatively little pavement pounding, since it incorporates the dirt roads paralleling Edmonds and not on the Edmonds itself. That will unfortunately change as the US 395 bypass construction progresses, but I'll take it while I can.

The Garmin did great, too bad I didn't. Damn, but Evan is fast these days. Or I'm getting old and slow. Probably both. The HR monitor on the Garmin had me at 93% a couple of times, and in Zone 5 for a good portion of the run, even on some of the typically "breath catcher" downhills. I can understand hitting the max zone on the "breath taker" uphills, but on the down: WTF?

According to the data, then, I'm running too hard and pushing things too much – reinforcing the getting old and slow theory. That indicates to me only one thing: time to ditch the HR monitor.

On Monday, my Garmin 405CX decided it no longer wanted to play nice. Coming off the charger, the display failed to update and pressing buttons failed as well. Following the manufacturers instructions, I then did the soft reset. That did it. Now I had a completely blank screen and no response. Great.
Following the threads I had seen on the Garmin forum, I tried a few of the suggested "fixes" all the while waiting for a response to Customer Support. Finally got a response today. Once they were "on the line", things progressed rapidly, though still to no avail. The damn thing is still dead in the water.
Garmin is sending me a new charging clip, believing that to be the issue. I withhold judgement until it gets here and I can give it a whirl. The next step after that is to replace the unit, which I've had only for a couple of months.
Sigh.