2010 21.5 EMC2389 erratic boot, sometimes normal?

[Cognus]

Friends this is my first venture in this forum after looking hard on web for clues to this. I have fairly useful tech skills with Windows devices, Mac, and handhelds but this one feels like a hardware issue that doesn’t show on testing
Per title it is a mid 2010 21.5 base spec i3, 4GB, running High Sierra on conventional HDD. Every boot up is of interest because it might boot “normal” meaning 2 minutes or it may take >20min, and be pretty hot by that point.
Otherwise, once booted it is pretty normal

When attempting to boot directly to Recovery it fails, with a variety outcomes. Most common is just chiming, sitting there, backlit, no logo, for anywhere from minutes to hours if left. Tried various key combos and sometimes goes to internet recovery where things look ok. Hard drive shows no errors

The video display once booted appears normal but is this all possibly interference from failing or faulting Radeon gpu?

 

[Cory Cooper]

Hello and welcome.

It could be a couple of things...failing hard drive, GPU, logic board.

If you have run Apple Diagnostics and it passes, then I would lean towards a failing hard drive. Have you run a full disk surface scan? Also, do you have an external drive with macOS installed that you can startup from?

C

 

[Cognus]

Thank you for responding!
I'm trying to get a fresh install of High Sierra, preferably APFS formatted [if I can somehow prove that this system can boot an APFS volume] on a new SSD. The current/original drive is working, and passes the rudimentary health scan in Disk Utility. I have read so much about failed Radeon gpu's that I have wondered if that guy fails in a way that is invisible to the eye but creates a storm of interrupts or something but have no evidence. Using a native apple usb keyboard, wired, I cannot get any sensible alternate boot as yet. I cannot get it to boot to diagnostics or local recovery. Twice, including right now, it has booted to internet recovery while trying to get it to boot to other things [safe mode, local recovery, diags]. I cannot prove that it will boot to an installer usb device since I can't get it to boot to a drive choice.
at a bit of a loss. It will boot, with no keys, to High Sierra and once booted it appears to work ok. I am working on trying to build a bootable SSD via USB port [again, haven't found reliable notes on the web that tell me it will actually boot once 'built']

right now it is stuck on a bare screen with just a wifi field and a passkey field for wifi, but 'blind' - that is it did not discover any wifi networks - there's nothing else on the screen and it is just looping after inputting the proper ssid name and passkey, so I'll shut down completely, drain power again, and try just a normal boot

again, this is a 21.5 imac 11,2 mid-2019 A1311 emc2389

Hello and welcome.

It could be a couple of things...failing hard drive, GPU, logic board.

If you have run Apple Diagnostics and it passes, then I would lean towards a failing hard drive. Have you run a full disk surface scan? Also, do you have an external drive with macOS installed that you can startup from?

C

 

[Cory Cooper]

Hello,

Sorry for the delayed reply.

macOS installs have been known to hang/fail when third-party RAM is installed. Do you have any thrid-party RAM in the iMac? If so, do you have a way to remove it and only have the original Apple RAM installed?

APFS was introuduced with macOS High Sierra, and normally any HFS disks will be updated to APFS during the install of High Sierra.

Do you have the ability to connect Ethernet to it to bypass the Wi-Fi issue?
Were you ever able to run Apple Diagnostics?

C

 

[Cognus]

Hello,

Sorry for the delayed reply.

macOS installs have been known to hang/fail when third-party RAM is installed. Do you have any thrid-party RAM in the iMac? If so, do you have a way to remove it and only have the original Apple RAM installed?

APFS was introuduced with macOS High Sierra, and normally any HFS disks will be updated to APFS during the install of High Sierra.

Do you have the ability to connect Ethernet to it to bypass the Wi-Fi issue?
Were you ever able to run Apple Diagnostics?

C

It's all good now, for the most part - running OCLP/Monterey, and I just don't let it step through the usual sleep modes. Automated start morning, shut down night, in between display off. Firmware is messed up in this one - that's the only explanation I can imagine [done a lot of tech work on intel platforms]. If it were a PC from any of the top 4 real makers, would be an easy fix with bios overwrite or upgrade. not so with apple - as best I can find, the last/final firmware patch for mid2010 was accompanying high sierra. Basically, no matter what input device used [wired/apple kbd or 3rd party, wireless, whatever], the intial bios load and coherence can take minimum of 3 minutes [fluke], average of 5 minutes, long can hang ultimately and reboots itself.
HOW do I find bootlog that is specific to the initial seconds/minutes? I went into the logs but the posts are all post-volume-boot unless I'm just looking at the wrong log altogether. would love to know what its waiting on - it may be a simple problem.

Supposedly/theoretically one should be able to download original CD disc image for this device and overwrite bootrom/systemware from the beginning, then roll through the patches but I have not been able to find this specific mid-2010 21.5 on the support site. found others in close proximity but not this one.

 

[Cognus]

someone tell me how to surface the bootlog details pls