The first step is to determine if the problem is software related. Restart your computer with the Disk Tools diskette and select Shutdown to see if it works properly. If it does, the likely cause of the problem is corrupted system software. A clean installation of system software is recommended to resolve the problem.
If choosing Shutdown still causes a Restart, try zapping PRAM. For more information on zapping the PRAM, for the Tech Info Library article "Macintosh: How to Reset Parameter RAM".
For Macintosh computers with lockable power switches, such as the Macintosh IIci and Macintosh IIsi, make sure the switch is not locked in the ON position. Rotating the switch 90 degrees to the left should release it so it is not in the locked on position.
If you determine the problem is not related to the power switch or system software, there are three possibilities: a defective keyboard, power supply, or logic board (in that order). As a quick test, disconnect the keyboard and mouse from the Macintosh and try a manual shutdown. If the Macintosh stays off, start replacing ADB devices. If not, have the power supply checked.
If the Macintosh still does not work properly, have the logic board replaced.
Article Change History:
24 Feb 1995 - Reviewed for technical accuracy.
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