Starts then shuts down

Question

i got home from work yesterday, went to start up my G4 it starts the boot phase with the apple logo and spinning gear and then shuts down.
i tried to reset motherboard, i checked both fans which are spinning (rpms?) but i do notice the heat sink is fairly warm as well as the video card but not sure if that's a normal warm.
i cannot unfortunately boot up to access any log's or system drives.
would disc warrior help? would booting from another OS on an external drive work?
when i hold the option button down to choose the start disc the computer will remain on forever so do i have an overheating issue, but when i select to boot the drive it goes to the apple screen, spinning gear and then shuts down.
help please.

Answer 1

job smith:
Do you get a normal startup chime?
You might try the battery removal advice you read... I'd suggest that perhaps you go a couple of steps further as well, though:
First of all, disconnect your peripheral devices when you're troubleshooting, which will eliminate them from potentially being part of the problem. Troubleshoot with only the keyboard, mouse, monitor, and power cord connected.
Try the following with the Apple Hardware Test disc inserted in the optical drive tray:
Disconnect everything from the Tower.
Disconnect the hard drive(s).
Remove the battery.
Depress the front power button and hold it in for a five-count.
Depress the PMU button and hold it down for a five-count.
Take a thirty minute break to insure the capacitors have drained.
Leave the battery out and the drive disconnected.
Close the side door, hook up and attempt to boot to the AHT disc.
If successful, run it and see what you get.
Reinsert the battery and try booting to the OS 9 or OS X install disc.
If successful, reconnect the startup drive and attempt startup from the install OS X disc again and run Repair Disk and Repair Permissions on the startup drive.
Boot normally to the startup volume.
Any luck? If not, please let us know where things failed.
Gary