RE: my big JR problem
Sorry, I should have gathered that from reading carefully !!
This is a long shot BUT check the lithium battery on the switch pcb. If thats okay, then try rebooting the CPU. Power the set up with the back off and look to the right of the CPU, there are 2 unvarnished contact points next to the cpu crystal. Short them out and hopefully the set will emit a beep. Turn the set over and the display should have an error message. Power off then power on and set should be back to life.
Let me know how you get on.