Entry point of Install.ps1 is the function Main. There you can see a call of function Update Bios with manufacturer, model, and BIOS version of the current system as arguments. Within that function other manufacturer can be added as a case for the switch.

switch($systemManufacturer.ToUpper())
    {
        "DELL INC."
        {
            $exitCode = UpdateDellBios $systemModel $biosVersion;
        }
    }

Here you can extend with another manufacturer. You also need a dedicated update function for the new manufacturer. Here we use a new Update Lenovo Bios function.

switch($systemManufacturer.ToUpper())
    {
        "DELL INC."
        {
           $exitCode = UpdateDellBios $systemModel $biosVersion;
        }
        "LENOVO"
        {
           $exitCode = UpdateLenovoBios $systemModel $biosVersion;
        }
    }

Check of exit codes must be extended or modified according to documentation of manufacturer's BIOS update or flash utility.

Our new Update Lenovo Bios function could look like the existing Update Dell Bios function and have models of the manufacturer listed and call a method to update a device with that model. Here Update Lenovo20BW function, which we call with the BIOS version of current system.

switch($systemModel.ToUpper())
    {
        "20BW"
        {
           $exitCode = UpdateLenovo20BW $biosVersion;
        }
    }

Once we have the Update Lenovo Bios function we create also a new Update Lenovo20BW function where we cover all required BIOS versions of available clients. And create a function which will flash device with new BIOS executable.

switch($biosVersion.ToUpper())
    {
        "JBET67WW"
        {
           $exitCode = UpdateLenovo20BWToJBET67WW;
        }
        default
        {
           $exitCode = UpdateLenovo20BWToJBET67WW;
        }
    }

In such a function Update Lenovo20BWTo JBET67WW we need a flash function for out new manufacturer which will look like existing Flash Dell Device function. New Flash Lenovo Device function would use the BIOS flash utility from website of this manufacturer with required parameters or execute BIOS update executable directly which can run on Win PE.

$exit Code = Flash Lenovo Device "WINUPTP64.exe";