There is an update re the A21 TP situation. I thought
the most likely thing was that I would need to replace
that internal power board. But it now seems to have
been some combination of a battery that is now
marginal (quickly drops from about 82% charge to
near-zero) and the transformer brick in particular.
I've confirmed this by means of spares lifted from
another A21. No more incidence of power switch
failures. From what I'm hearing, it is not uncommon
for the transformer bricks on various devices to go
bad. First time I've run into this, though.
Jordan