Can't boot iMac after fresh installation

[luisfromamora]

Dear all,

I have this 2009' A1225 and I can't get past the boot screen. I also can't get to the hardware diagnostics.
I had no problem recovering to Yosemite (Cmd+R), running safe mode (very slow), single mode or booting from a memory stick to install Mojave.

However, if I try to boot from the just installed partition, after a few seconds with a progress bar, I get a white/grey screen and that's it. After a few minutes it reboots and the whole process repeats. I've tried NVRAM reset and SMC reset without results.

I'll open the iMac soon to look for explanations and even swapping hardware around, but I find it strange that I can go through the whole installation process without problems and I can't boot.

Thanks in advance.
Regards,
--
Luis

 

[DeltaMac]

That's often the sign that your hard drive is failing.
Swap that out. This is a good time to move to an SSD.

What process did you use to patch the Mojave install so you could install it on your 2009, 24-inch iMac?
Maybe you could choose to install El Capitan? At least that is supported natively.
(if the hard drive is failing, then the big task of erasing/reinstalling will likely not make things work better.

 

[luisfromamora]

Installing Mojave (dosdude1) was my last try. When I tried the reinstall from recovery (partition, not web recovery, now that I think of it), it proposed me Yosemite. Still, the end result was 100% identical, after 25% on the progress bar, I get an empty blank/grey screen.

I'm typing this message from a 2011 MPB with dosdude's Mojave too. I've also installed it on a MacPro3,1 without a glitch. It's a pity that I can't run the AHD (Apple Hardware Diagnostics) from a pen drive, can I?

If it was a problem with the hard drive, wouldn't the Disk Utility have detected a problem? Wouldn't it hang too during the OSX installation?

I'll eventually replace the HDD once I open up the iMac (waiting for the suction cups to remove the glass) but I would like to have a better idea of the troubleshooting steps I should try.

 

[Fishrrman]

OP:

You can't install Mojave because that computer cannot BOOT FROM Mojave.

Refer to this:
https://everymac.com/systems/apple/...o-2.66-24-inch-aluminum-early-2009-specs.html

According to everymac.com, the last OS that iMac can boot from is El Capitan, OS 10.11.x.

It might be possible to coax Mojave onto it using an unsupported patch, or something like that...

 

[DeltaMac]

OP did mention using a dosdude1 Mojave installer, so I think that should work.
But, of course, the Mojave install will change the format of the boot drive to APFS, another part that can be hard on a marginal hard drive.
Even if Disk Utility does not expressly fail, you may notice that a reformat might take longer than normal (a minute or more, compared to a more normal 10 seconds or so). And, you are installing a system that is even less happy on a spinning hard drive than Yosemite, even when the hard drive is perfectly good.

to OP - the hardware test SHOULD boot and run from a flash drive. All you need to do is restore the disk image for the appropriate AHT to a flash drive.