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13" aluminum unibody, 2.0 or 2.4 GHz Core 2 Duo processor.

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Mac Stuck at Boot, Probably Firmware

Hey all at iFixit.

Today I booted my Mac to this (see attached image). The Mac literally does nothing now. I can’t shut it down by holding the power button, I can’t restart it. The only way to shut it down is by physically disconnecting the battery.

I notice the progress bar loads and then the Mac restarts if I hold the power button at startup (programing mode), but then restarts back to this thick progress bar.

I can’t access boot manager, so I’m convinced this is an issue with the firmware. I have the Mac OS X Snow Leopard install DVD, but I don’t know how to use it if I can get to boot manager.

What’s my next step?

Block Image

UPDATE: Bad news.

I have successfully bricked the machine :P

I tried reseting the NVRAM a few times and force shutting it down by disconnecting the battery, and now my power light on the front of the Mac flashes once every three seconds or so. And, no, the machine does not boot any more.

Well, this was undoubtedly a firmware issue, I know you could use firmware restore CDs back in the day, but I don't have that! Could I download a .dmg of one and burn it to a CD?

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I think you have a deeper issue within the logic board than a firmware issue. This series used a NVIDEA I/O combo chip which often failed. Basically, the CPU is not able to communicate with the systems peripherals.

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@danj - Yikes. Well, I’m saving the headache of trying to solder a new board. I have a spare logic board that I’ll use. Thank you! I would like to know, though: why would you think this is a bigger issue than just firmware? I’m just now starting to get into the world of flashing SPI chips.

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@jadonlyon - Firmware issues most happen when the system is going through the update process and gets hung so the firmware update is not completed. The other possibility which is remote is probing the chip causing it to get corrupted. This series is quite old so its OS or firmware is not going under change so that removes the larger risk, and as you stated you had just restarted your system from the day before I don’t think the firmware is the issue at all and from experience the combo GPU & I/O chip often failed so my money is on that.

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@danj - Makes sense. It’s a shame these logic boards just give up like they do, it makes preserving old Macs very difficult.

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Jadon Lyon crwdns2934231:0crwdne2934231:0
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