display flickering on Dell all in one (can't do anything)

I suggest you create another Admin account to get at the other things you want:-

1 Enable the Built-in Admin

Enable or Disable Built-In Administrator account - TenForumsTutorials {you'll need to use Option 5, enabling it at boot}

2 Use it to create a new password-protected local Admin account

Add Local Account ... - TenForumsTutorials
Change to Admin account type - TenForumsTutorials

3 Write the password down somewhere secure yet accessible.
4 Disable the Built-in Admin

Personally, I always have two additional password-protected local Admin accounts. I use one for troubleshooting & I keep the other one unused so it cannot be corrupted & is ready for an emergency.

Note that, since the display flashes in Safe mode, it is not a third-party driver issue. It is either the computer hardware or Windows [including MS drivers].
- You can tell the difference by finding out if the display flashes in Bios. I do not know what 'video test' you mean; if it is a built-in Dell one then perhaps you've already been in the Bios.

- If the display flickers in Bios then, unless Dell offers an updated Bios that claims to fix this particular problem, I'd hold off updating the Bios for now.
- If the display does not flicker in Bios then, if Dell offers an updated Bios, I'd update the Bios.

- See if there is any relevant guidance in Dell Support or in their user forums.


Best of luck,
Denis

Just a note, the All-in-Ones I've dealt with used motherboards quite similar to those in a Notebook with biggest difference being the external keyboard and mouse so any information about the same type issue could be useful such as a loose connection between the board and the display panel. The All-in-Ones tend to be more difficult to work inside of because of the stand fastened to the housing and their weight.

Harry,

HarryD said:

It does not flash in BIOS.

That's good news. The problem would seem to be in Windows [or in a relevant MS hardware driver but not a third-party driver].
Personally, I'd jump the gun and run these even though there's no definite indication of a cause yet
- Try another user account even if you have to create one for the test.

Add Local Account ... - TenForumsTutorials
I really cannot see it being user profile related but …

then, if the fault persists,
- SFC

SFC-DISM - TenForumsTutorials

then, if the fault persists,
- Repair install

Repair Install Windows 10 with an In-place Upgrade - TenForumsTutorials

Whilst backing up first would be sensible, a Repair install should not affect installed applications or user data

HarryD said:

It was pretty simple to remove the stand and back cover. I'll double check all the connections to and from the MB. I'm leaving the back cover off until the problem is fixed.

Your successful Bios test probably eliminates a connection issue.

Denis

Try3 said:

Harry,


That's good news. The problem would seem to be in Windows [or in a relevant MS hardware driver but not a third-party driver].
Personally, I'd jump the gun and run these even though there's no definite indication of a cause yet
- Try another user account even if you have to create one for the test.

Add Local Account ... - TenForumsTutorials
I really cannot see it being user profile related but …

then, if the fault persists,
- SFC

SFC-DISM - TenForumsTutorials

then, if the fault persists,
- Repair install

Repair Install Windows 10 with an In-place Upgrade - TenForumsTutorials

Whilst backing up first would be sensible, a Repair install should not affect installed applications or user data

Your successful Bios test probably eliminates a connection issue.

Denis

I won't be able to add a user account, I can't use the mouse or keyboard while it's flashing. I can't do anything as the owner forgot his password to the admin account.

Harry,

All I can think of is running SFC when booting from a Win10 installation disk. That is described in Option 1 of the SFC tutorial.

Other than that, I think you are going to have to replace the current HDD with a new SSD/HDD and reinstall Windows.
Clean Install - TenForumsTutorials

You might be able to recover some or all of the user's own files from the old HDD but that's not looking very likely from your earlier comments.

I'm afraid that I cannot think of anything less drastic.

Best of luck,
Denis

Try3 said:

Harry,

All I can think of is running SFC when booting from a Win10 installation disk. That is described in Option 1 of the SFC tutorial.

Other than that, I think you are going to have to replace the current HDD with a new SSD/HDD and reinstall Windows.
Clean Install - TenForumsTutorials

You might be able to recover some or all of the user's own files from the old HDD but that's not looking very likely from your earlier comments.

I'm afraid that I cannot think of anything less drastic.

Best of luck,
Denis

The owner just brought me a new hard drive. How can I clean install Windows 10 (what he presently has) and keep (or transfer) all of his files?

- - - Updated - - -

I'm downloading the Dell recovery program to my computer and creating a bootable USB drive with Windows 10 on it. I'll then manually transfer his stuff over and give him the old HDD (if this works).

- - - Updated - - -

I inserted the USB drive and started from it. It asked if I wanted to do a repair, I said yes and entered the password for my network.
It's now downloading Windows, updates and drivers. No flashing so far.

Harry,

HarryD said:

The owner just brought me a new hard drive.

HarryD said:

How can I clean install Windows 10

HarryD said:

I'm downloading the Dell recovery program to my computer and creating a bootable USB drive with Windows 10 on it.

By 'Dell recovery program' I take it you mean what Dell calls the 'Dell Windows Recovery Image'.
If it has not changed recently, the Dell recovery program is a [roughly] 5GB "ISO" file from which you create an installation USB and it already contains all the Dell hardware drivers required.
I imagine that you have already checked the instructions for the relevant model [those for my model are at How to create and use the Dell Windows recovery image - Dell US and I imagine they are all pretty much the same].

HarryD said:

I inserted the USB drive and started from it. It asked if I wanted to do a repair, I said yes and entered the password for my network.
It's now downloading Windows, updates and drivers.

I'm confused by this comment.
- The 'Dell Windows Recovery Image' already contains Windows and all the relevant Dell drivers.
- I appreciate that you can choose to get all updates during the installation procedure so that's no surprise.
- If you are using a new SSD/HDD there is nothing to repair & that's not an option I would expect to see after booting from the USB. It will clean install using pretty much the same procedure as the generic TenForumsTutorial I linked to earlier.

HarryD said:

… keep (or transfer) all of his files?

HarryD said:

I'll then manually transfer his stuff over and give him the old HDD (if this works).

If you can read the old HDD then you will be able to copy back the owner's files.
Many of the files will be in C:\Users\username but people can choose to put files in many different places.

HarryD said:

No flashing so far.

Good. I would not expect this problem to re-appear because the checks you did indicated that it was a Windows fault rather than a hardware defect.


I can see that you last posted an hour ago so you've probably already completed the installation.
Given that you used the 'Dell Windows Recovery Image' it should self-activate without even having to go online. You can check at Settings, Updates, Activation.

All the best,
Denis