I resoldered J1.

C1 looks like this:



Turned it on, same thing.

What happens is it makes the happy ding at startup, if I tap the side I can see the screen flicker trying to come on (and can often see the floppy ? icon), however when I tap it like this it makes a noise like a "dzzzt" or a cat-bell sounding noise.

Then eventually it gives up doing this, and tapping it further causes the machine to reboot itself (evident from the startup sound)