If you have the original OS disks? You could try booting from those and running apple hardware test by holding down "D" as the computer tries to start up. That will only work if you can get the disk in though. If you can run the Apple hardware Test, run the extended test. That should tell you if there is a logic board problem. If you can't even do that... then I am sorry to tell you that it is most likely a logic board problem.
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If you have the original OS disks You could try booting from those and running apple hardware test by holding down "D" as the computer tries to start up. That will only work if you can get the disk in though. If you can run the Apple hardware Test, run the extended test. That should tell you if there is a logic board problem. If you can't even do that... then I am sorry to tell you that it is most likely a logic board problem.
If you have the original OS disks? You could try booting from those and running apple hardware test by holding down "D" as the computer tries to start up. That will only work if you can get the disk in though. If you can run the Apple hardware Test, run the extended test. That should tell you if there is a logic board problem. If you can't even do that... then I am sorry to tell you that it is most likely a logic board problem.