Catalina update to 10.15.7 bricked by 2019 Imac

This update broke my Imac 2019 model which already run catalina and all minor updates since it came out.

The update to 10.15.7 didn’t complete and hang on “Estimating remaining time…”

I left it for more than 35Hrs and it didn’t progress at all. would not move.

Now the OS would not start, recovery boot didn’t help, safe mode does not work as well.

Tried the disk utility and noticed that the Macintosh HD volume and the Macintosh HD DATA volumes can not be erased, as the system can’t unmount them.

Unmount is impossible, no matter how i tried.

I started the IMac with external USB disk (containing the Catalina installer), and got the same results, (can’t unmount) same results with Mojave installer disk.

Also tried to force unmount from terminal, which also hangs forever and does not work.

in dmsg i saw that the “device is unreadable…”

Diagnostic (holding D or SHIFT + D) also does not work.

Contacted Apple support which after hearing all the above, simply said: “go to a lab”.

So to sum up, i’m almost 100% sure that this is not an original, 1TB, one year old SSD issue.

i don’t think that it’s a coincidence that the SSD started to have its first ever “issues” during this update.

The worst thing that could happen with an IMac these days just happened.

This Device is one year old, in brand new condition. and i don’t have any way to fix it.

no lab is available for us right now, as we can’t go out anywhere far due to the Corona situation in my country.

I even have (3 month old, but still...) a full backup of the IMac on an external device. (Time Machine)

And this update doe snot allow me to use it in anyway.

can’t go back, can update…

If anyone have an idea, i’m ready to try almost anything to recover / reinstall it from scratch.

Thank you.