Permanent overheating damage?

I just rediscovered my dreamcast love a few weeks ago. I was playing MSR, but swapped to TV last sunday, leaving my DC on.

It's in a closed cabinet and I forgot about it until my new DC peripherals arrived by air mail last friday (new controllers, extension leads, ...). I hooked everything up, tried to boot up my dreamcast and... no picture anymore, no booting sound.

I tried with & without game, I tried over the VGA-box and over a normal SCART lead, but the picture doesn't show anymore. Even now after resting the console for over a day, I have no result whatsoever. :(

Does anybode know wether it could have overheated or something? Is this permanent?