What to do if Microsoft hasn’t fixed my Xbox Series X in 4 straight returns, what should I do?

I would have your electricity checked. If 4 seperate Xboxes have failed the same way, the problem is likely external

I am having same issue on my Xbox series x what should I do

You're welcomed.
Keep me posted if needed, Dustless.

Thank you for the help, I will try these and update you whether it works or not.

Hello, Dustless. I'm Arturo, a community user like you, and I'll be glad to provide assistance with your inquiry today.

Based on the information you provided, I would like to suggest the following potential solutions:
(Skip the ones you already tried)

A. Run the Gaming Services repair tool and then verify if the sign in feature works after that.

https://support.xbox.com/help/games-apps/troubleshooting/gaming-services-repair-tool > Please expand the field that says “Downloadable version” and follow the steps.

B. Search “Services” by using the Windows search functionality and look for the following services:

IP Helper
Xbox Live Auth Manager
Xbox Live Game Save
Xbox Live Networking Service
Gaming Services

For each service: Right-click on the service > Properties.
In Startup Type, set the service to Automatic.

If the service isn’t started, click Start > Apply > OK to save changes, restart your PC and try again.

Note: In case GamingServices can't be modified, skip that one.

C. Right-click on the Windows button and select PowerShell (run as an administrator).

Then, run the following command: (You may want to copy and paste the entire command)

Get-AppXPackage -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_. InstallLocation)\AppXManifest.xml"}.

This command can take a while to end, but when the process ends, you should be able to type in the PowerShell window.

After that, please restart your computer and try using the Xbox app again.

I'll remain attentive to your feedback.

Regards,

Arturo.