Early G5 2.0 dual.
My previous G5 died (probably Logic Board, possibly power supply).
Got another one.
On the internal "A" drive the hard drive (750 GB Seagate) is divided into 2 volumes. One is the system and apps (125 GB, about 85% full).
This hard drive successfully started up the new G5 several times. It then wouldn't boot completely. It would start to boot and the apple would get covered by a black rectangle.
I then ran TechTools 5.05 on the machine and this drive, starting up with the TechTools e-drive. All hardware tests were okay. However, "Volume Structures" on the system & apps volume failed. This volume was grayed out (unmounted). No problems were reported for the other volume on this hard drive.
I rebuilt the system & apps volume. In doing so, the new directory was reported as having "unusual changes."
The problem with the incomplete bootup ending in the black rectangle continued.
I also booted up from the Tiger system disk and used First Aid to repair the system & apps volume. However, even after repair, the "mount" command did nothing.
So, at this point both TechTools and Tiger install disk report no problems with the volume, but show it as unmounted, and the Tiger install disk will not mount it. When I click the "mount" command nothing happens. The computer starts up fine from the Tiger install disk, TechTools e-drive, or an external eSata backup drive. But the internal "A" drive system & apps volume does not mount and booting to it ends in the black rectangle covering the apple.
It doesn't seem like this is a hardware problem, since the other volume on the "A" hard drive mounts properly.
Is this a matter of the system on system & apps" volume being hopelessly corrupted, beyond what First Aid and TechTools can fix, even though they report fixing the directory corruption? Is there any solution short of erasing the entire hard drive?