TR8620 can't turn it off

[TXbirder]

To print, I turn on the printer with the power button.  When finished, I press the power button and nothing happens.

I have to go to my PC and open the IJ Printer Assistant Tool and select  POWER OFF.

Why does the power button work properly to turn the unit ON, but not OFF?

JGLTX 

[jrhoffman75]

I have the TR8620a.

I just press the Power button, hold for a few seconds and the release. Light flashes and powers off.