You're absolutely right. I used this digit to evoke a high blinking rate, beyond my ability to evaluate, and said "If you see what I mean" to allude to that. I should have been more explicit.

The manual is on a CD, and N800 users don't need those CDs to pair/"synchronize" the keyboard; the paper manual is very basic and doesn't adress such issues (If I read well).

However, I followed your suggestion more directly. My first attempt was with used batteries: no red LED light -- no light. I then tried relatively new batteries: the green LED light came back like before.
Thanks!!!

Now I'm back to the pairing problem.

Considering the price of USB female-to-female adaptors, I decided to try the USB host program with a USB keyboard, as explained in the Tablet School tutorial. I'll inform readers of the outcome. A rubber keyboard would be quite handy.

But thanks, I'm still interested in using again my bt keyboard.