iMac 27" 2017 not booting after blade upgrade

[Mackata]

Hi out there,
please help me:
I put a new blade into my iMac 27 2017 letting the old 2TB HD of the fusion drive stay.
Now I can choose whatever volume I want but boot process stops after 20 sec and I get this sign (see att.).
I hope somebody can help me.
All the best for 2021 for all of you

 

[Juicy Box]

Did you defuse the Fusion Drive prior to removing the OEM SSD?

 

[Mackata]

No, unfortunately not. What can I do now?

 

[Fishrrman]

"No, unfortunately not. What can I do now?"

Hope that you have a backup.

What was on the fusion drive is almost certainly ... gone forever.

You could put the original SSD back in, and see if the iMac can be booted again, but I don't think there's a good chance that will work, either.

So...

The only thing I can recommend is to try this:
1. Boot to INTERNET recovery
Command-OPTION-R

2. Open disk utility and choose "show all devices" from the view menu (important step)

3. ERASE both drives. DO NOT attempt to "fuse" them again, even if disk utility asks if you wish to do that.

4. Install a clean copy of the OS onto the SSD.

5. Restore from your backup, IF you have one.

 

[Mackata]

After a while in internet recovery there ist this sign

 

[mdgm]

Which version of OS X did you have installed prior to replacing the blade SSD?

A search on the web suggests this error is related to your Wi-Fi network not being suitable for Internet Recovery. If you can't configure your Wi-Fi network suitably you could try an ethernet connection instead.

 

[Mackata]

I had Catalina and Big Sur installed. How can I avoid Wifi?

 

[mdgm]

Search the web for the wifi requirements for using Internet recovery and configure your wifi appropriately or connect your Mac to your router using an Ethernet cable.

 

[Fishrrman]

I'm wondering if the alert the OP got was due to the fact there's a non-Apple SSD installed where internet recovery expects to find an "Apple" SSD...?

 

[Juicy Box]

No, unfortunately not. What can I do now?

If you need the files on the Fusion Drive? You could reinstall the OEM Blade SSD. As long as you didn't wipe anything, I don't see why this didn't work.

What can I do now?

Can you describe exactly what you did, step by step?

It is hard for us to give suggestions no knowing what exactly happened.


In addition to telling us what you did, let use know:
Did you back up your data?
Is is a bootable back up?
If you didn't back up your data, is it important, do you need it?
Do you have access to another Mac in case you need it? If so, what model?

How can I avoid Wifi?

Use Ethernet or have another recovery partition somewhere.

I put a new blade into my iMac 27 2017 letting the old 2TB HD of the fusion drive stay.

I personally wouldn't take the time to open up these Macs just to leave the hot spinning drives inside. If you open your Mac again, I suggest taking out the HDD and installing in an external enclosure if you want to use it.