Stuck In Diagnostic Startup

I messed up my computer and need some real expert help to straighten this one out. Any assistance / suggestions would be appreciated. Details are below:

MY SYSTEM:
Dell E6400
Upgraded from Win 7 to Win10 Pro (so directories after c prompt show old folders and Win10 upgrade folders)
4gb Ram

The computer was really working good until I made the following System Changes:
Took the following steps:
1. Went to: All Apps Menu
2. Then: Windows Administrative Tools
3. Then: System Configuration
4. Under General Header
5. Then: Selected “DIAGNOSTIC STARTUP”
6. Then: Clicked APPLY and SAVE
7. Then: I shut down the computer and restarted it.
Now only the background will load when I boot up, no login will appear and nothing will load. See PROBLEM below.

Before I made the change, the computer startup was perfect as follows:
1. Start Computer
2. Windows 10 logo
3. Background Picture
4. Click on screen to show password logon
5. Logo on and desktop appears.

PROBLEM: Computer process now after the change:
Start Computer
Windows 10 logo
Background Picture only (scenic background)
Click on screen to show password logon
The background stays on (scenic picture) but dims when I click to try to get the logon bar. Only picture on screen – no
words or images
Cannot do anything else
After a minute the screen brightens and I can click on it again to try to bring up the ‘logon PW field’ and it (scenic background picture) dims again.
When I have the blank screen no commands are recognized (Win + R, Win + X etc…)

Note:
The only way I can get to C prompt is by using the Win10 installation thumb drive. I tried to do a repair using the
Installation app on thumb drive but it failed and told me it could not make the repair.
I can reach the BIOS via F12 on start up.
The system now may not be recognizing any startup files
I can email screen shots of the directories visible after the C: prompt if it’s useful.

I believe I somehow may have disabled the default start-up instructions and correction wills need to be made via the C: prompt.

Does anyone have recommendations on how to restore the 'set-up'?

Thanks.

Solved as follows:
Reached Safe Mode by powering off two times then getting Diagnosing PC mode.
Then - Auto Repair
Then - Advance
Then - Troubleshooting
Then - Advanced
Then - Selected number 4 Safe Mode
Entered Safe Mode and reached the System Configuration and found that ALL of the startup applications and drivers were indeed turned off. I turned all back on, saved and rebooted. All is good now.

I hope this helps someone else.

Also go to: You Tube: https://youtu.be/2f-GorXWkoc

Bizguy said:

Solved as follows:
Reached Safe Mode by powering off two times then getting Diagnosing PC mode.
Then - Auto Repair
Then - Advance
Then - Troubleshooting
Then - Advanced
Then - Selected number 4 Safe Mode
Entered Safe Mode and reached the System Configuration and found that ALL of the startup applications and drivers were indeed turned off. I turned all back on, saved and rebooted. All is good now.

I hope this helps someone else.

Also go to: You Tube: https://youtu.be/2f-GorXWkoc

Thank you sooooooo much, you saved my bacon man!!!!

You helped me too! Thanks very much

Thanks Bizguy - solved my issue too. Much appreciated!

Bizguy said:

Solved as follows:
Reached Safe Mode by powering off two times then getting Diagnosing PC mode.
Then - Auto Repair
Then - Advance
Then - Troubleshooting
Then - Advanced
Then - Selected number 4 Safe Mode
Entered Safe Mode and reached the System Configuration and found that ALL of the startup applications and drivers were indeed turned off. I turned all back on, saved and rebooted. All is good now.

I hope this helps someone else.

Also go to: You Tube: https://youtu.be/2f-GorXWkoc

Hi all,
I'm facing the same problem on a surface pro4 with windows 10. I don't know how to get diagnosing pc mode! Can you help me? Thanks!

Hi, I got into this pickle the same way as the author.
To get cured on a surface / surface book.
When you power on keep holding power button for 10 seconds. This crashes the boot and after several attempts it enters diagnosing mode as per video in YouTube link.
Phew

Top man. Thank you!:)

Bizguy said:

Solved as follows:
Reached Safe Mode by powering off two times then getting Diagnosing PC mode.
Then - Auto Repair
Then - Advance
Then - Troubleshooting
Then - Advanced
Then - Selected number 4 Safe Mode
Entered Safe Mode and reached the System Configuration and found that ALL of the startup applications and drivers were indeed turned off. I turned all back on, saved and rebooted. All is good now.

I hope this helps someone else.

Also go to: You Tube: https://youtu.be/2f-GorXWkoc

I'm in this same jam but cannot find "Diagnosing PC mode"