Same problem "cojack" posted 5/25/06. Answered by GX1_MAN.
Did not find a solution posted.
Computer will not power on when pwr switch is pressed. Bestec Model ATX-250-12E power supply failed (found capacitor burned off printed circuit board after removing). Replaced with 500w CoolMax M-500B. Emachine Model T2984, OS Windows XP Home, CPU Intel Celeron 2.93GH, 512mb ram, mother board Intel D845GVSR. Downloaded mother board manual and checked connections. Reseated RAM chip and all PCI boards. No fans, lights, mouse or keyboard operate. LED on mother board lights. Suspect machine is in suspend state (S1 or S3). Removed battery and left out 4 hours to discharge CMOS. Any suggestions?