with the radio powered off, hold the A=B button down and turn on the radio.
The important concept is to press and hold
the A=B button while you turn on the power ON...
yes I did 100 times
If you are absolutely doing what the book recommends and cannot get a reset, the other option is to disconnect the memory battery and allow the radio to sit idle for a day or two. Some CMOS chips can retain data for a week without power, and it's possible to glitch memory when a new battery is installed. That's why a full reset (the nuclear Armageddon option) is recommended as standard operating procedure after a battery transplant.
But... If all else fails, pulling the battery for a while can reset the radio back to factory defaults.