A less invasive method to resuscitate a Mac that won't start up after a power outage is to reset the eMac's switching power supply (which can be latched up by a power glitch) by removing the power cord from the side of the eMac (to remove the trickle current drawn by modern electronics even when nominally off) and waiting 15+ minutes. Then reattach the power cord and start the Mac. That's easier than turning the eMac over and unscrewing the RAM access cover to get at the PMU reset button. It also avoids the small but non-zero possibility of mis-pressing the PMY reset button; pressing PMU reset for too long (more than about one second) or pressing it repeatedly can potentially crash the PMU, rendering the logic board unusable (a failure not covered under any warrenty).
