No boot after command line debacle.

dubstep_steve · June 6, 2021

Long story short after being crashed in gtav by another modder my internet connection was disrupted. I attemtped to restart pc to fix this and it bluescreened after reboot. I got fed up and removed my d and e drives and clean installed windows again on my c drive (500gb crucial m.2 nvme). This initially worked and i was able to boot windows. After going through and doing all the updates i installed latest available nvidia driver for my gtx1080. This was okay and still stable until after a few minutes i attempted to change my screen refresh rate. As soon as i clicked display adapter 1 properties or whateve that blue link says my pc crashed. Blue screen again. I belive it said the "bad system config" or something like that. Not wanting to go through a reinstall again and assuming there was no corrupt windows files due to clean install i tried my hand at some command line work. Big mistake. SEE BELOW FOR COMMAND LINE SEQUENCE. After entering this command line with a shaky step midway when it asked for a new partition path or something like that for the ufi (11 numbers or enter for none?) i hit enter and continued with the final line of the command prompts below. I then reset pc and since then everything is on but it will not boot. Also there is no display output on hdmi or display port to either monitor. Gigabyte boot led constantly illuminated which means "; if the BOOT LED is on, that means you haven't entered the operating system yet". I'm not sure if this is even fixable at this point so i really just need to know if this command line sequence is isolated to the drive or if it affects the bios in some way? Can i just buy a new m.2 drive and install windows on it and hope that i fix whatever else is going on after i can actually boot again?

Please send everyone

Motherboard: Aorus b360 gaming 3

CPU: Intel 9400f i5

GPU: Galax gtx1080

RAM: 16gb Kingston hyperx 2666mhz

M.2 SSD: Crucial 500gb nvme

PSU: Cougar 850W gold modular

Windows 10 Installation Media:

Insert the Media (DVD/USB) in your PC and restart.
Boot from the media.
Select Repair Your Computer.

Select Troubleshoot.

Choose Command Prompt from the menu:

Type in the command:

Diskpart

Type in the command:

List disk (Note which disk is your Boot drive number mine is 0)

Type in the command:

Sel disk 0

Type in the command:

List vol (Note which volume is the EFI partition mine is 4)

Type in the command:

Sel vol 4

Type in the command:

assign letter=V:

Type in the command:

Exit

Type in the command:

V:

After you have assigned a drive letter Using Diskpart You can format the EFI partition:

Example: if you assigned a letter V to the partition the command would be:

format V: /FS:FAT32

Type in the command:

bcdboot C:\windows /s V: /f UEFI

TudorFinalBosz · June 6, 2021

@dubstep_steve

It seems you tried to restore the EFI partition by rebooting with a Windows USB drive, then using DISKPART to try and rebuild an EFI partition.

It's not that simple and I think you just formatted that volume 4 as FAT32 but the bcdboot command didn't restore the EFI partition.

It's weird that you'd have the EFI partition as the 4th volume. It should be more like the first or second. If it's the 4th, then it might be located after the main partition where you have the Windows installation.

I think this might be rescuable, but it's hard.

First of all, you should be able to start the computer with the USB Windows media drive and see it bootable in the Bios. That has nothing to do with any display drivers, the motherboard loads some basic display driver emulation and runs it on the CPU. So, even if you don't have an iGPU you should be able to see display output. Or if you have a GPU without drivers, again, it should still work, the emulation would run on the CPU but could still output.

In order to restore your EFI partition, you need to make sure you are placing it before the actual Windows installation. So when you use Diskpart to create that FAT32-formatted space of about 100MB and assign a letter, that needs to have a disk offset (ie, address on the disk) that is lower than where the one where the OS partition starts.

You can take a look at this tutorial to get an idea on how this can be done:

https://zamarax.com/2021/02/10/how-to-restore-deleted-efi-system-partition-in-windows-10/

I followed this step by step and managed to restore an EFI partition that was completely deleted probably by mistake or through some error done by some AOMEI software.

The structure on the disk that you need to have in order for Windows to work properly is this:

EFI System Partition — 100 MB (partition type — FAT32);
Microsoft Reserved partition — 128 MB (partition type — MSR);
Primary Windows partition (the partition containing Windows).

Normally, a recovery partition is the first, so typically that means about 512MBs in front of the EFI partition. There might also be some empty MSR space in between these, left for the purpose of aligning partitions.

But if we simplify things, you only need a working EFI partition for the BIOS to see it as a viable bootable Windows disk. So, you could focus only on rebuilding that, if you have the patience. It can take an hour or so of very carefully entered commands in Diskpart.