Cant enter firmware password on Mac Pro 5,1 I need to enter recovery mode and finally remembered my firmware password using the magic at https://www.cnet.com/news/use-the-calculator-to-reveal-a-macs-firmware-password/

but the padlock screen won't let me enter anything, not even move pointer with the mouse.  How can I enter my firmware password?
answered at 
https://forums.macrumors.com/threads/firmware-padlock-screen-wont-accept-password.2144758/#post-26602612

Removed a memory stick and rebooted into recovery and from there I was able to remove the firmware password (which recovery didn't see as being active, so I created a new one and then disabled it)