If you have some good clear pictures of the board (especially the motherboard top & bottom) that will help. Please post them here. The M72 hardware issue could be as simple as the ribbon cables not being securely making contact, bent pins on the bottom of the motherboard or a cut trace. Upload some pictures on what the boards look like and the error on screen
I'm suprised no one gave you an answer yet. Where are the knowledgeable repairers?
I felt for you and asked a local repairer:
"RAM NG 5 is the audio RAM. Could be the RAM chip itself, the logic chips around it or a trace."