"Wrong passcode. Try again." Partial solution

Here is the scenario. You lock your Mac for safe keeping either using the utility to set the firmware lock or by using FindMy to lock your machine remotely. Then someone tries to use the machine and they make several guesses for the passcode and eventually they, and you are locked out. The screen says “Wrong passcode. Try again.” But there are no boxes where you can enter the code. If you reboot the machine, it tells you that it has been disabled and to wait 60 minutes, but after the 60 minutes, you get the “Wrong passcode” message with no means to enter the code. I had this happen to me, though for the life of me don’t know how or who set the lock in the first place. The only solution I found here was that I had to take it back with my proof of purchase to Apple. But they are 100 miles away and I discovered they won’t honor a proof of purchase from a 3rd party retailer. Incredibly frustrating, especially since I found discussions about the missing boxes to enter the code going back 8 years! And Apple hasn’t fixed this problem? Good grief! I’ll post the solution to the missing boxes below.