After not using my Dual Bootable DP 1.25 GHz MDD G4 for a couple of months, it's now freezing during the boot process.
What's weird is that it boots in Target Mode just fine, and when connected in this mode to my G5 Quad, it actually boots the G5 Quad in Target Mode just fine! The G4 drive shows in fact as the boot drive on the G5 Quad's monitors.
I was able to boot off a retail Tiger 10.4.6 disk, so I did an erase and install of a fresh Tiger OS 10.4.6, which I promptly updated to 10.4.11. After trying and failing umpteen times to boot off the HD, even in safe mode, I ended up being utterly unable to get either of the Super Drives to open normally, so I had to resort to the straightened paper clip trick to retrieve the install DVD.
Now even the paper clip fails to open either of the optical drives.
I have twice wiped the HD from the G5 Quad after booting up in Target Mode, and installed fresh copies of Tiger 10.4.11 as described, with the Tiger install DVD in the SuperDrive of the G5 Quad.
Since in Target Mode the G5 Quad boots just fine of the G4 HD, I think I can rule out the Hard Drive.
I think I can rule out the battery too, as it boots fine in Target Mode and in the regular boot process it sometimes gets as far as playing the OS fresh install music after going through the registration process.
I do have the original install disks with AHT 2.0.2 that came with the G4, but I can't get the optical drives open to insert the disk in either one of them.
I'm thinking it could be bad RAM, but why would the optical drives be stuck, both of them??!
I'd be most grateful for any tips as to what to try next.