The corrupted SDS8202 was eventually revived with an
externally-drive firmware update. I had full function back on
the 4th rewrite, after making sure that any stored settings
were manually re-written with non-corrupted values.
Even the rotary encoders seemed to have been restored
to function. Go figure. That's an issue with many other
models, written off as oxidation or aging. Perhaps it's
worth while raising the issue more forcefully with the
The firmware file was labelled with this unit's full serial number,
so I'm not sure it's of use to anyone else. Why so cagey about
an apparently successful firmware revision?
The under-voltage battery operation is still too dangerous to
allow to occur - if it still can result in firmware corruption.
I'll be looking into possible hardware mods to rectify that.