The problem happens with this board from burnt wires shorting the input side, to a simple hardware glitch that can kill the board. A common misconception when you order the board from the counter is it’s programmed to your exact machine. That is not the case. RCD puts out a base file for the serial provided.  A very good practice before changing the bad board is going through the old board configurations. It will take about 30 to 45 minutes on the scrolling marquee. When you hit a setting and you don’t know what it is hold Enter and Escape for about 5 seconds and the display will read it out to you. This also works for the navigator which is highly recommended if you work on a lot of these (Navigator Part Number 30GT-911—062). Once you have the settings, swap the Enable/OFF/Remote switch to off and let the machine shut down. Lockout the power and swap the MBB. Once the MBB is swapped return power to the unit. With the enable switch off, go through your configurations and verify there are the same as what you wrote down. Once that is complete set the enable switch to where it was before, and you are ready to go.