Windows 10 drive rendered inoperable during OSX 10.15.4 Upgrade

[RuC2020]

Hi all, I've been running OSX 10.15.3 without problems this last month, & booting 'via' a USB clover bootstick rather than going the full post-inatll route.

With the release of Multibeast 12.1.0 I decide to brave a 'proper' Multibeast post-install & upgrade to 10.15.4

After quite a few tense re-boots & being dumped out back to BIOS setup a couple of times, 10.15.4 finally stuck & everything is running great.

One issue though, is that my Windows 10 drive (an entirely separate SSD) now no longer works at all.

I can no longer boot Windows, from either the Clover screen, or Directly from the (F11) BIOS screen. I just get a flashing cursor .

Before the 10.15.4 + Multibeast upgrade, I could happily swap between them both.

Should I have physically unplugged the Windows SSD during OSX upgrade ? is this a common problem or have I done something wrong doing the process?

Is there any way back for my Windows drive, or must I scrub it & re-install everything again. I have tried booting from my Windows 10 install USB & using the rubbish 'drive repair' function but with no joy.

Cheers

 

[P1LGRIM]

Moved to Multi booting.

 

[Big-W]

You should be able to repair that from uefi shell. Take a look at the following thread;
https://www.tonymacx86.com/threads/...on-gone-after-bios-update.211715/post-1409404

 

[RuC2020]

You should be able to repair that from uefi shell. Take a look at the following thread;
https://www.tonymacx86.com/threads/...on-gone-after-bios-update.211715/post-1409404

Thanks for getting back to me. That thread look terrifying. I'm not that techie, & have got this far by more luck than judgement !

Just to be clear, my WindowsNTFS drive does still show up in Clover (pic#1)...when when I boot from it I just get a blinking cursor (pic#2).

If I select it from the 'F11' boot screen (Its the SATA Kingston, third option down pic#3) ...I get this error message (pic#4)

Any chance of explaining in simple terms to steps to fixing it?..& If I can't (going back to my other question) will just reinstalling windows on that SSD from scratch make it work, or will that Kill my Mac install? I had OSX & Windows all running quite happily before I did the multibeast post-install. Do the problem always come with the territory ?

Many thanks again for humouring a beginner with your reply !

 

[Big-W]

If your bcd data is corrupt preventing Windows booting, reinstalling should work. If you're going to resort to that, then you may as well try and fix it....nothing to lose. Just take the OSX disk out and boot from Clover USB

 

[Big-W]

Take a look at this as an alternative.

 

[RuC2020]

If your bcd data is corrupt preventing Windows booting, reinstalling should work. If you're going to resort to that, then you may as well try and fix it....nothing to lose. Just take the OSX disk out and boot from Clover USB

Understood. And will booting Windows Via my Clover USB stick fix the Windows SSD..or do I still need to do some command line black magic...?...& might that then break OSX?

 

[RuC2020]

Take a look at this as an alternative.

...thank you...but this is so far beyond what I currently understand...I thought I had a handle on how this all worked before I did the multibeast post-install step, but I feel like a total newbie again...I was actually happy booting from by Clover USB stick, but I could get the OSX 10.15.4 upgrade to stick that way..

So (& I'm sorry if this is a real beginners question)...do both Windows & OSX actually modify code on the motherboard when they install? I thought they were 'quarantined' (2 metres apart! ) on their own drives?

 

[Going Bald]

Launch MacOS terminal and enter diskutil list. Post pic of results.

Windows and Mac OS do not make any changes to the BIOS - rather the BIOS is the interface that tells the OS how to interact with the board chipsets firmware.

Also, mount the EFI partition of the Mac OS drive and check contents - should be folders for:
EFI
EFI/Apple
EFI/Boot
EFI/Clover

If you do not have these, then you made a uh-oh and installer Clover to the Windows drive EFI.
This is why we recommend removal/disconnection of all drives except the target drive when installing any OS.

 

[RuC2020]

cheers..here we go..

OSX is on an internal nVme drive
Windows is on an SSD SATA drive