Thanks for the replies folks.
I guess my OP was not descriptive enough...sorry.
The reader did not operate or respond; all I got was the shifting charge LED & chirping.
Now, many hours later, it actually booted up and is responding quite normally - so I will go with the idea that it was a 100% empty battery (for now...).
It is the oldest 6" EZReader I've seen, from 2008 according to the info screen.
Since I have a choice of f/w versions from the spare I got some months ago, I'll consider upgrading it to newer f/w at some point after checking to see that it works normally & holds a charge.
If it does turn out to be bad somehow though - that'll be OK as it'll be spare parts to keep around in case there is breakage.