Sorry for needing the hand holding.

When I place the case 499 code in Marlin_main.cpp I get the following compile error:

Marlin_main.cpp: In function 'void process_commands()':
Marlin_main.cpp:3065: error: 'Invalidate_EEPROM_Settings' was not declared in this scope


When I place the void Invalidate_EEPROM_Settings() code in ConfigurationStore.cpp (I don't have Configuration_Store.cpp) I get the following error after the sample code below:

#include "Marlin.h"
#include "planner.h"
#include "temperature.h"
#include "ultralcd.h"
#include "ConfigurationStore.h"

void Invalidate_EEPROM_Settings()
{
char bogus_ver[4] = "xyz";
char confirmation[4] = "???";
int i=EEPROM_OFFSET;

EEPROM_WRITE_VAR(i,bogus_ver);

i=EEPROM_OFFSET;
EEPROM_READ_VAR(i,confirmation); //read stored version

if (strncmp(bogus_ver, confirmation,3) == 0)
SERIAL_PROTOCOLLNPGM("EEPROM Settings invalidated.");
else {
SERIAL_PROTOCOLLNPGM("EEPROM Settings not invalidated.");
SERIAL_PROTOCOLPGM("Read Version: [");
SERIAL_PROTOCOL(confirmation);
SERIAL_PROTOCOLLNPGM("]\n");
}
}



ERROR:
ConfigurationStore.cpp: In function 'void Invalidate_EEPROM_Settings()':
ConfigurationStore.cpp:11: error: 'EEPROM_OFFSET' was not declared in this scope
ConfigurationStore.cpp:13: error: 'EEPROM_WRITE_VAR' was not declared in this scope
ConfigurationStore.cpp:16: error: 'EEPROM_READ_VAR' was not declared in this scope