$SitecoreInstanceUri = "https://helixsite.local"
$Username = "admin"
$Password = "b"
$SitecorePackagePath = "C:inetpubwwwroothelixsite.localApp_DatapackagesHelix.Project.Website.Master.update"

#Create a new script session
$session = New-ScriptSession -Username $Username -Password $Password -ConnectionUri $SitecoreInstanceUri

Write-Host "Installing Sitecore update package '$SitecorePackagePath' on '$SitecoreInstanceUri'"

$jobId = Invoke-RemoteScript -Session $session -ScriptBlock {
    $package = $using:SitecorePackagePath
    Write-Log "Installing Sitecore update package '$package'"
    Install-UpdatePackage -Path $package -UpgradeAction Upgrade -InstallMode Install
} -AsJob -Verbose

if (!$jobId) {
    Write-Host "No jobId was created. Please check if your Powershell Remoting is activated on the target instance '$SitecoreInstanceUri'"
}

#doneScript is the script that gets executed every 5 seconds and checks the state of the executed script. It returns a custom PowerShell object with Name, IsDone and Status
$doneScript = {
        $backgroundScriptSession = Get-ScriptSession -Id $using:jobId
        $isDone = $backgroundScriptSession -eq $null -or $backgroundScriptSession.State -ne "Busy"
        [PSCustomObject]@{
            "Name" = $backgroundScriptSession.Id
            "IsDone" = $isDone
            "Status" = "$($backgroundScriptSession.State)"
        }
    }

try {
    $keepRunning = $true
    while($keepRunning) {
        #Execute the doneScript and check the response.
        $response = Invoke-RemoteScript -Session $session -ScriptBlock $doneScript
        if($response -and $response.IsDone) {
            $keepRunning = $false
            Write-Host "Polling job $($response.Name). Status : $($response.Status)."
            Write-Host "Finished polling job $($id)."
        } else {
            Write-Host "Polling job $($response.Name). Status : $($response.Status)."
            Start-Sleep -Seconds 5
        }
    }
} catch {
    if ($_.Exception.Message -eq "ScriptSessionNotFound,Cognifide.PowerShell.Commandlets.ScriptSessions.GetScriptSessionCommand") {
        Write-Host "Package installation triggered application pool recycling."
    }
    else
    {
     throw
    }
}


Write-Host "Sitecore update package installed."
Stop-ScriptSession -Session $session

Polling job d8400253-9f9e-4718-89d5-0dd633bf3bf6. Status : Busy.
Polling job d8400253-9f9e-4718-89d5-0dd633bf3bf6. Status : Busy.
Polling job d8400253-9f9e-4718-89d5-0dd633bf3bf6. Status : Busy.
Polling job d8400253-9f9e-4718-89d5-0dd633bf3bf6. Status : Busy.
... This keeps running for few minutes ...
Polling job d8400253-9f9e-4718-89d5-0dd633bf3bf6. Status : Busy.
Polling job d8400253-9f9e-4718-89d5-0dd633bf3bf6. Status : Busy.
Polling job d8400253-9f9e-4718-89d5-0dd633bf3bf6. Status : Available.
Finished polling job d8400253-9f9e-4718-89d5-0dd633bf3bf6.
Sitecore update package installed.

Installing item '/sitecore/system/Settings/Forms/Submit Actions/Send E-mail'
Installing item '/sitecore/system/Settings/Forms/Submit Actions/Submit Action'