MP 1,1-5,1 MP 5,1 Stalls at logo, won't boot

[johnvision]

mid 2012 MP 5,1 suddenly will not pass the apple logo loading screen. The loading bar stalls at around 75% but reaches 100% eventually, however stops there and never proceeds further.

Apple store have assessed and can not figure it out. I have since installed another backpane and the same issue occurs

 

[JedNZ]

Can you expand more on your setup (it helps if you add your system specs to your signature), including any hardware upgrades that have been made, what version of macOS you’re using and what sort of drive it’s installed on (HDD, SSD, M.2 etc) and where it’s installed (eg SATA II bay, M.2 PCIe adapter in PCI slot 3 etc).

 

[johnvision]

Thanks,
It's the dual 2.4 (12core) mid 2012. minimal upgrades, only ram and SSD

Ram is 32gb
SSD in one of the sata HD bays
Radeon HD 5770
High Sierra

 

[Soba]

I'm curious if you'll get any farther with a clean macOS install, so have you tried removing the existing drive and doing a clean install of High Sierra from a USB installer onto a blank drive?

 

[johnvision]

Apple store tried all of that to no avail. Haven't tried this with the replaced logic board though

 

[johnvision]

UPDATE

I just tried an old HDD that I believed to be an old version of the current SSD's data that I am currently trying to use in the failing 5,1 machine.

However it was in fact an old HDD from a previous 3,1 Machine I had. And... the failing 5,1 now boots normally using this HDD.... Albeit with Snow leopard

Still interested in anyone's advice on what may have occurred with the machine not booting with the SSD. This SSD had been runnings normally for 3 years. And the 5,2 machine couldn't be revived even with apple doing an attempted reinstall.

 

[KeesMacPro]

You could remove the SSD, boot from the old HDD and download the High Sierra installer to install on the old HDD.
Note that a requirement for HS is 10.8 or newer, so you will have to upgrade to e.g. El Capitan first.

Once running HS on the old HDD, you could install DriveDX , install the SSD and check if it's failing/EOL.
If the drive appears healthy, apparently the OS installed got corrupted so you could erase it and do a clean HS install on it .
This is assuming you have a backup to recover all data with Migration Assistant after the clean install.

Since you replaced the backplane , the BootROM version is unknown (at least to the reader) , what version is it now?
What brand and model SSD is installed?

How to download and install macOS - Apple Support

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