Support Assist update will not install

Here is what worked for me:

Uninstall via "Revo Uninstaller Pro (Trial)" or "Advanced Uninstaller Pro (Trial)"

• https://www.revouninstaller.com/ 
• https://www.advanceduninstaller.com/ 

Download from the author's website, no where else, please. A simple uninstall process from control panel or windows settings is not sufficient. Allow one of these apps to aggressively uninstall, remove associated folders, and delete associated registry keys. Even afterwards, we have to verify everything is entirely uninstalled. If you don't see it installed, check for next item on list.

• SupportAssist App from Microsoft App Store
• SupportAssist if you see second installation which is from .EXE or .MSI 
• SupportAssist Agent
• SupportAssist OS Recovery Plugin for Dell Update
• Dell Update
• Dell Command Center
• Dell SupportAssist Remediation
• Dell Digital Delivery

Before doing anything else, continue by deleting some folders manually which were unable to be removed otherwise, and if you don't see the folder, check for next item on list. Copy/Paste the filepath because some folders ARE hidden. 

• C:\Program Files\Dell
• C:\Program Files (86)\Dell
• C:\ProgramData\Dell Help & Support
• C:\ProgramData\DellDataVault
• C:\ProgramData\Dell.DataVault.DataCollector.SubAgent
• C:\ProgramData\SupportAssist
• C:\ProgramData\SupportAssistBusinessClient
• C:\ProgramData\PCDr
• C:\ProgramData\OS Recovery Tool
• C:\ProgramData\SARemediation
• C:\ProgramData\SupportAssistHardwareDiagnosticsSubAgent
• C:\ProgramData\SupportAssistOsRecoverySubAgent
• C:\ProgramData\SupportAssistServiceSubAgent
• C:\ProgramData\SupportAssistSoftwareDiagnosticsSubAgent
• C:\ProgramData\OS Recovery Tool
• %AppData%        Delete Dell Folder
• %AppData%        Delete PCDr Folder

Before doing anything else, continue by opening your Start Menu by clicking the Windows icon on the bottom left of your screen. Type "Regedit", right-click it, and select to "Run as Administrator". You need to delete some registry entries manually which were unable to be removed otherwise, and if you don't see the folder, check for next item on list. Copy/Paste the filepath to save time in the search.

• HKEY_LOCAL_MACHINE\SOFTWARE\DELL\SupportAssistBusinessClient
• HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Dell\SupportAssist
• HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Dell\SupportAssistAgent

Before doing anything else, continue by rebooting the computer immediately. 

**Now, please relax and allow this to be a slow process**

1. When you log back in, you need to download SupportAssist from their website:
   
   • https://www.dell.com/support/contents/en-us/article/product-support/self-support-knowledgebase/software-and-downloads/supportassist 
2. Right-Click, Run as Administrator when done downloading. Do not open the app when it finishes, close the installer when done and reboot.
3. When logged back in, Launch SupportAssist. Let this application load slowly, and sit open for a few minutes. Then close it. This allows all low priority processes to start fully as they are sequentially triggered off a timer. In the background, those services ARE probing your PC to check hardware and reference database in cloud for corresponding drivers you need. The services also check your other "Dell" essentials which we previously uninstalled. These will either install slowly, automatically over the next 24 hours, OR you will see the prompt for them appear after your next reboot. Do not reboot until the next day. When it does, log in and let it sit for an hour. Let it finish properly setting up what is needed post-log-in, which would not be permitted until log-in. 
4. After 24 hours has passed, and the app has been opened for half an hour, your first move is to check for WINDOWS updates, and if none then proceed. If there were, then reboot before proceeding - allowing SupportAssist to open and sit for half hour before proceeding. 
5. Check for driver updates in SupportAssist now. If this is unsuccessful, you must install the latest Microsoft .NET Runtime available for your version of windows, as well as Microsoft .NET SDK, and enable in "Turn Windows Features On or Off". Reboot. 
6. Check Windows Updates, if none proceed. If updated, reboot. 
7. Launch SupportAssist, let sit half hour, check updates. If failed, see if it was able to install Dell Update for you. If not, manually install it from the driver page for your Dell model. Check for updates within Dell Update after install. Reboot.
8. Check Windows updates, reboot. This is making sure what Dell Update has done, is also receiving Windows-corresponding updates. This also double-checks that .NET Runtime and SDK are also updated to latest versions compatible with your OS. When we finally see Dell Updates and Windows Update are having 0 new updates, you no longer have to reboot so keep this cycle of checking, installing, rebooting until reaching this point. 
9. Now open SupportAssist, let it scan your hardware, now check for updates. You should see the progress bar have a % other than 0 and reach completion with results of NONE or needed updates. You are golden if you are now seeing this. 

This is a combination of solutions sourced from Dell Community, and the major contributor is from Martin Schiemenz (Dell Enterprise Support Services) comment on 04-29-2019 to the following post: 

https://www.dell.com/community/SupportAssist-for-PCs/Inspiron-17-5000-Problem-Support-Assist-is-not-updating-and/td-p/7291840 

It was also a major contributor to see how deep the rabbit hole goes in the following community post:

https://www.dell.com/community/SupportAssist-for-PCs/quot-Successful-Application-Reconfiguration-quot-and/m-p/7870925/highlight/true#M91454 

I obviously came up with some steps of my own toward the end after a couple dozen hours of trial and error attempting what others were successful trying. It is apparent that everyone's computer is different so I performed these exact steps as a sort of "FULL SWEEP" after understanding the underlying problem. Dell Update is more of a plug-in for SupportAssist which is the main engine behind the process running into error conditions due to possible Windows Store trying to install the MS APP version along-side or instead of the .EXE or .MSI version which is downloaded from the Dell website directly. That download is the most maintained version and is specifically for HOME PC. You will want a ENTERPRISE PC version if you have Windows Enterprise OS rather than Pro or Home. 

I do not work for Dell or Microsoft, I am just a technology-enthusiast offering my personal solution to anyone who hasn't found success yet in troubleshooting with other suggested routines online. 

Dell Inspiron 7577

Windows 10 Pro, Version 21H2, Build 19044.1889