Valid XML fails to be read by powershell due to & symbol

Question

Below is my xml that is provided by a third party and cannot me altered.

C:\Temp\test.xml:

<?xml version="1.0" standalone="yes"?>
<parameters>
<setParameter name="ConnectionString" value="mongodb://svc-dev, connectTimeoutMS=300000&w=majority"/>
</parameters>

Below powershell command was meant to load the XML but it fails with error:

PS C:\Users\meuser> $xml = [xml](Get-Content "C:\Temp\test.xml")
Cannot convert value "System.Object[]" to type "System.Xml.XmlDocument". Error: "'=' is an unexpected token. The expected 
token is ';'. Line 3, position 90."
At line:1 char:1
+ $xml = [xml](Get-Content "C:\Temp\test.xml")
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidArgument: (:) [], RuntimeException
    + FullyQualifiedErrorId : InvalidCastToXmlDocument

The bigger picture is that I wish to check if my xml is empty or contains entries for setParameter as below.

# Check if the XML contains any entries for setParameter
if ($xml.parameters.setParameter) {
    # Check if all the name and value attributes are empty
    $isEmpty = $xml.parameters.setParameter | ForEach-Object {
        $_.name -eq "" -and $_.value -eq ""
    } | Measure-Object -Maximum

    if ($isEmpty.Maximum -eq 1) {
        Write-Host "XML RESULTS: All the name and value attributes are empty."
        #exit 1;
    } else {
        Write-Host "XML RESULTS: The XML contains GOOD entries for setParameter."
    }
} else {
    Write-Host "XML RESULTS: The XML does not contain any entries for setParameter."
    exit 1;
}

Note: i cannot and do not wish to change the contents of the test.xml.

I may further want to read key-value in the xml make changes and save it to a new xml file.

Kindly help me overcome the error.