management-scripts/Start-Windows10UpdateAssistant.ps1

## Make sure the computer is running Windows 10
If ( ([System.Environment]::OSVersion.Version).Major -ge 10 ) {

    ## Make sure the endpoint isn't already running 1909
    If ( ([System.Environment]::OSVersion.Version).Build -lt 18363 ) {
        
        ## Set the directory where the Windows Update Assistant will be downloaded to
        $DOWNLOADS = "${Env:TEMP}"

        ## URL to the 1909 version of the Windows Update Assistant
        $URL = 'https://download.microsoft.com/download/9/b/f/9bf08afb-bfd8-488a-9ce6-90134cea4d8f/Windows10Upgrade9252.exe'

        ## Uninstall previous Windows 10 Update Assistant
        If ( Test-Path "${Env:SystemDrive}\Windows10Upgrade\Windows10UpgraderApp.exe" )
        {
            Write-Output "Uninstalling existing Windows 10 Update Assistant"
            Start-Process "${Env:SystemDrive}\Windows10Upgrade\Windows10UpgraderApp.exe" -ArgumentList '/ForceUninstall' -Wait
        }

        ## Create download directory if not using $Env:TEMP
        #If (!( Test-Path $DOWNLOADS ))
        #{
        #    Write-Output "Creating "${DOWNLOADS}"
        #    New-Item -ItemType Directory -Path $DOWNLOADS
        #}

        ## Download Windows 10 Update Assistant
        $FILENAME = Split-Path $URL -leaf
        If ( Test-Path "${DOWNLOADS}\${FILENAME}" )
        {
            Write-Output "Deleting existing installer: ${DOWNLOADS}\${FILENAME}"
            Remove-Item "${DOWNLOADS}\${FILENAME}" -Force -ErrorAction SilentlyContinue
        }
        Write-Output "Downloading ${URL} to ${DOWNLOADS}\${FILENAME}"
        (New-Object System.Net.WebClient).DownloadFile($URL,"${DOWNLOADS}\${FILENAME}")

        ## Install and run the Windows 10 Update Assistant
        If ( Test-Path "${DOWNLOADS}\${FILENAME}" )
        {
            Write-Output "Launching installer: ${DOWNLOADS}\${FILENAME}"
            Start-Process -FilePath "${DOWNLOADS}\${FILENAME}" -Wait
        }

        ## Delete the downloaded program
        If ( Test-Path "${DOWNLOADS}\${FILENAME}" )
        {
            Write-Output "Deleting installer: ${DOWNLOADS}\${FILENAME}"
            Remove-Item "${DOWNLOADS}\${FILENAME}"
        }

    } Else { Write-Host "This endpoint is already up to date." }

} Else { Write-Host "This endpoint is not running Windows 10." }