Using VGA Monitors to Fix Blacked-out iMacs
In "Update Firmware Before Installing Jaguar!," in TidBITS 653 we outlined an arduous hard drive-swapping process to recover iMacs which have been rendered unusable by installing Mac OS X 10.2 Jaguar. If an affected iMac has a VGA video output port, an easier option may be to connect it to an external VGA monitor. If the external monitor mirrors your iMac’s display, you should be able to update the system’s firmware directly without attempting to dismantle your iMac… or paying for a motherboard replacement.