[BRLTTY] Refreshing problems?

[Jason White]

Have you tried the braille display in self-test mode?

On the 40 cell version, you have to press the buttons above cells 1, 2, 39
and 40. If the firmware is similar in your 80-cell display, this should
work if you press buttons 1, 2, 79 and 80.

According to the documentation, the self test raises and lowers the dots
in each cell, one after another, and will also show which keys are pressed
on the display.

This may enable you to find out whether you have a hardware problem.
According to the manual, any communication received by the braille display
in self test mode terminates this mode.