iBook G4 screen only turns on for login

The problem may be hardware, such as low battery power or inability for an old

battery to hold a charge; there also could be a problem with hardware, in that

an old computer could have a worn or failing hard disk drive, with bad sectors.

Troubleshooting to find the cause of the issue(s) may involve trying to get it to run

and then once started, be sure it is working off the AC Power Adapter; then try to

boot the computer in SafeBoot mode. Then you could look into system logs in the

Console utility (in utilities folder) and check those reports or logs from the exact

time the problem occurred. Some problems may not register if the computer fails

before they can be written to the hard drive.

•OS X: What is Safe Boot, Safe Mode? - Apple Support

•Mac OS X - Using Disk Utility to Repair a Disk (also: to start from installer media)

https://kb.wisc.edu/helpdesk/page.php?id=3810

•Resetting PowerBook and iBook Power Management Unit (PMU) - Apple Support

•OS X Mavericks: Reset your computer’s PRAM - same as earlier OS X PRAM reset

•Mac notebooks: Troubleshooting power adapters with a barrel-type connector - Apple Support

•Calibrating your Mac notebook's battery for best performance - Apple Support

•PowerPC-Based Mac notebooks: Identifying the right power adapter and power cord--US - Apple Support

If you have the system install-restore DVD media for the OS X installed in the iBook,

that is one way to try & test the computer. If the hard disk drive has failed, you still

could boot from the install DVD media (hold C key on startup with disc in optical drive)

and wait for an undetermined amount of time, for the computer to start from the DVD

so it can be used to test & perhaps repair, or learn of the hard disk drive status.

Given the age and vintage of both the computer and its moving parts, the HDD has

likely experienced some glitch. Could be some damage to sectors on the drive, or

perhaps it was way too full and had other file damage. You could erase & re-install

a new operating system from the booted install DVD media. If no optical media was

included with your iBook G4, you may have to look for retail versions of system OS

which may be increasingly more difficult to find. That is another topic, since the DVD

media which is supposed to accompany the computer have part numbers. The retail

DVD for say, Leopard 10.5 (won't work on iBook G4 800MHz) has a different label

than original media that was with the Mac, new. Those were gray labelled discs.

Most iBook G4 models with faster than 867MHz processor, could use Leopard 10.5

from retail install DVD. Many of the last models shipped with Tiger 10.4 on gray DVD.

Hopefully you can perform some troubleshooting and have those system install DVDs.

Since this is a long distance call, please deposit 50¢ for the next Five Minutes... 🙂

Could be the hard disk drive has sector damages or other faults, and needs to be

replaced with another ATA/IDE older type hard drive. If the computer were checked

over by an expert, and if the HDD was determined to be the cause of failure, then

the answer and path would be clear...

If the computer model is of the correct vintage and you have original installer media

that shipped with it, (Panther, Tiger, etc) it should work if correct to the exact build.

A later retail DVD would be OK if you don't have the original gray-label install kit.

However without a better diagnostic method, the trial-and-error route may be prone

to causing damages to other items inside the computer, since many fragile parts and

wires are inside that could become sources of trouble after replacement of a HDD.

You could try your luck with shipping the computer away for diagnostic testing and

estimate on repairs to include parts, labor, and an offer of a guarantee on the work.

Since iBook G4 models (unless in pristine condition with complete OEM kit, in box)

are not expensive, it is still possible to get PowerPC Apple portables that have been

repaired, at about the asking price for dubious ones that appear on craigslist...

The PowerBookmedic site and also wegenermedia site both show older computers;

and you could probably send a portable away to either one for diagnostic and repair.

I'd had good results + guaranty, with a vintage computer sent to wegenermedia.com.

Could be, if the computer is worth keeping, it may be worth paying to fix correctly.

Or, you could look for a working similar computer to get by for now, at low cost.

So far, my iBook G4 12-inch mid2005 only needs a replacement battery; perhaps a

newertechnologies from OWC would do. Also they have a legacy SSD for older

portables that would work well in an iBook or PowerBook G4 at macsales.com.

Not sure what to suggest, other than tamper with the unit; carefully test the computer

and try an external FireWire400 enclosure with the correct chipset to allow for Mac OS

booting from the FireWire enclosure; if you can find one that'd work with a 2.5-inch

HDD portable size drive, you could test the computer & if you could make it work from

a system on external hard drive, later the HDD could be swapped. Those iFixit guides

can be helpful to some extent. Troubles include remembering where all the different

lengths of screws came from, and all the tiny wires and breakables, which may fail.

In any event...

Good luck & happy computing! 🙂