I just received this from Anycubic. I was asking about doing the PID tuning in case I want to upgrade my hotend. Here is what I got which seems incorrect since you were able to save your settings. Were you able to figure out how to list the current EEPROM settings? The 8bit board used M501 from what I have read.
Email from Anycubic:
And I want to tell you that eeprom of MEGA04 cannot be used. And it cannot be modified by instructions.
Have a nice day~