firmware password lost, can't perform recovery boot
I have a mac pro 2013-2019 ( ME253CT/A) that was purchased used by a manager years ago. He has moved on, and the original SSD died. I've purchased a new SSD for it, but the screen shows a gray lock and a password entry space. I've found that this is a firmware password, but have no way to talk to the old manager to find out what it is. How do I reset this so we can install a new OS and begin using this beast again?
Mac Pro