Run powershell from task sequence of MDT

Question

I have realised a powershell script who set the bios parameters during the intallion of windows 10 or windows 7 by MDT, I integrated it in my server MDT like a 'Run Powershell Script' from the task sequence of windows but is not working, if I test my script in winpe is working well but after installation the os, if i chek the bios nothing is happen. I integrated my script by the os task sequence, right click in the task sequence, clic on add=>general=>run powershell, then I put the path and the name of my script like %SCRIPTROOT%myscript.ps1. For the execution policy i put it like "Run Command Line" it is : powershell.exe -command "Set-ExecutionPolicy Unrestrictebd".

This is my script for windows 10, may be i miss something

    $computerManufacturer = (Get-WmiObject win32_computersystem).manufacturer
if($biosManufacturer -ceq "Dell Inc." -or $computerManufacturer -ceq "Dell Inc." ){

  #Activation du mode UEFI
        $bios= Get-WmiObject DCIM_BIOSService -namespace root\dcim\sysman 
        $bios.SetBIOSAttributes($null,$null,"Boot Mode","2")
        #Desactivation du legacy
        $bios.SetBIOSAttributes($null,$null,"Enable Legacy Option ROMs","1")
         #Activation du secure Boot
        $bios.SetBIOSAttributes($null,$null,"Secure Boot","2")     

         }

The second one for windows 7 is

$biosManufacturer = (Get-WmiObject win32_Bios).manufacturer
$computerManufacturer = (Get-WmiObject win32_computersystem).manufacturer
if($biosManufacturer -ceq "Dell Inc." -or $computerManufacturer -ceq "Dell Inc." ){   echo  $computerManufacturer

        #Desactivation du mode UEFI au detriment de Legacy
    $bios=Get-WmiObject -class DCIM_BIOSService -namespace root\dcim\sysman 
    $bios.SetBIOSAttributes($null,$null,"Enable Legacy Option ROMs","2")
    $bios.SetBIOSAttributes($null,$null,"Boot Mode","1")            

        #Desctivation du secure Boot
        #$bios.(Get-WmiObject DCIM_BIOSService -namespace root\dcim\sysman ).SetBIOSAttributes($null,$null,"Secure Boot","1")        

        } 

elseif($computerManufacturer -ceq "HP" -or $computerManufacturer -ceq "Hewlett-Packard"  ){

 #Activation du mode UEFI du mode UEFI
    $bios=Get-WmiObject -Namespace root/hp/instrumentedBIOS -Class HP_BIOSSettingInterface
    $bios.SetBIOSSetting("Configure Legacy Support and Secure Boot", "Legacy Support Enable and Secure Boot Disable","")    
    $bios.SetBIOSSetting("UEFI Boot Options", "Disable","")
    $bios.SetBIOSSetting("Legacy Boot Options", "Enable","")

     }

If any one have any idea I will apreciate it!!