how to use different credentials inside an invoke-command - powershell

Question

I am currently trying to get a value from a different server. So I am connecting to a server using $sessionUsername and $sessionPassword but then I need to use different credentials to get the information that I require.
I am unsure as to how I can do this, so far I have tried to do a Start-Job and a Start-Process inside the Invoke-Command and even another invoker command but this has not worked.
$sessionUserName = "mysession"
$sessionPassword = "sessionPassword"
#$sessionUserName = "LON\user"
#$sessionPassword = "user"
$serverAddress = "the address"
$securePassword = ConvertTo-SecureString -AsPlainText -Force -String $sessionPassword
$credentials = New-Object -TypeName System.Management.Automation.PSCredential -ArgumentList $sessionUserName,$securePassword
$session = New-PSSession -ComputerName $serverAddress -Credential $credentials
$username = "LON\differentuser"
$password = "different password"
$PSS = ConvertTo-SecureString $password -AsPlainText -Force
$cred = new-object system.management.automation.PSCredential $username,$PSS
Invoke-Command -Session $session -scriptblock {
#Start-Process "C:\StuckApps\powershell.exe" -Credential $args[0] -ArgumentList "-file C:\StuckApps\connect.ps1"
$args[0].GetNetworkCredential().username;
$args[0].GetNetworkCredential().password;
$t = {
$args[0].GetNetworkCredential().username;
$args[0].GetNetworkCredential().password;
$conn = New-Object System.Data.SqlClient.SqlConnection
$conn.ConnectionString = "Server = Theserver.co.uk; Database = m; Integrated Security = true;"
$conn.Open()
$command = New-Object System.Data.SqlClient.SqlCommand
$command.CommandTimeout = 0
$command.CommandText = "exec dbo.AlphaBoard_GetStuckApps"
$command.Connection = $conn
$rows = $command.ExecuteReader()
$dt = New-Object System.Data.DataTable
$dt.Load($rows)
$number = $dt.Rows.Count
$conn.Close()
return $number
Write-Host "Hello"
}
Start-Job -ScriptBlock $t -Credential $args[0]
#Start-Process powershell -ArgumentList '-executionpolicy','bypass', $t -Credential $session
$number
} -ArgumentList $cred
$number
$previousNumberPath = "C:\bamboo-home\xml-data\build-dir\INT-SAM-JOB1\number.txt"
The $args[0].GetNetworkCredential().username; inside the invoke-command shows me that this is passing the credentials in, but how can I use them? I am not sure what I am doing wrong? I can't seem to get the $number variable back, how can I do this?
The main problem I have is the error
This command cannot be run due to the error: Access is denied.
Which I am unsure why this is happening as on the server itself it I run:
Start-Process powershell.exe -Credential $cred -ArgumentList "noexit", "-file C:\StuckApps\connect.ps1"
which I have also tried on my current script, it works fine, but using this on my script shows an access denied. I have already got on the server via the first invoke-command why can't I get the same result?