This is one way to record what's happening. The transcript and variable values will be written to a file in the $LogPath directory:

<#Added TS Variables for if using during OSD.  Creates Variable SMSTS_BiosUpdate, and sets to TRUE. (For Future Use)
        http://powershelldistrict.com/how-to-read-and-write-sccm-task-sequence-variables-with-powershell/

       #>
$tsenv = New-Object -COMObject Microsoft.SMS.TSEnvironment -ErrorAction SilentlyContinue
$tsenv.Value("SMSTS_BiosUpdate") = "True"

#Create Log Path
$LogPath = $tsenv.Value("_SMSTSLogPath")

#Get Bios Password from File
#$BiosPassword = Get-Content .\Bios.txt

#Create Model Variable
$ComputerModel = Get-WmiObject -Class Win32_computersystem | Select-Object -ExpandProperty Model

#Get TRANSCRIPT File Name (No Extension, used to create Log File)
$TRANSLogFileName = $LogPath + "\" + $ComputerModel + ".log"

Start-Transcript -Path $TRANSLogFileName
Write-Host "Current Directory: $((Get-Location).Path)"    # Note where relative paths refer to
Write-Host "ComputerModel: $ComputerModel"
Write-Host "PSScriptRoot: $PSScriptRoot"
Write-Host "Direct child directories found in current directory:"
Get-ChildItem . -Dir |
    ForEach-Object{
        Write-Host "    " $_.Name
    }

# the FILE name of the exe to be copied
$ComputerModelExe = "{0}\{1}\*.exe" -f $PSScriptRoot, $ComputerModel
Write-Host "SOURCE exe file path to be used: $ComputerModelExe"

if (Test-Path -Path "$PSScriptRoot\*.exe"){
    Write-Host "FATAL: there are one or more EXE files in the directory $PSScriptRoot"
    Get-ChildItem "$PSScriptRoot\*.exe" |
        ForEach-Object{
            Write-Host "    " $_.Name
        }
    Throw "FATAL: there are one or more EXE files in the directory $PSScriptRoot"
}

#Copy Bios Installer to the root of the package - the Flash64W didn't like when I left it in the Computer Model folder, because it has spaces. (Yes, I tried qoutes and stuff)
Copy-Item $ComputerModelExe -Destination $PSScriptRoot  # copy exe file from its child directory
[array]$x = Get-ChildItem $PSScriptRoot\*.exe           # verify that only ONE file
if ($x.count -gt 1){
    Write-Host "FATAL: multiple EXE files found in $PSSCriptRoot after Copy-Item"
    $x |
        ForEach-Object{
            Write-Host "   " $_.Name
        }
    Throw "FATAL: multiple EXE files found in $PSSCriptRoot after Copy-Item"
}

$CopiedComputerModelExe = $x[0].FullName
Write-Host "The copied exe file is here: $CopiedComputerModelExe"

#Get Bios File Name (Uses the Bios EXE file in the same folder)
$BiosFilePath = $CopiedComputerModelExe
Write-Host "BiosFilePath: $BiosFilePath"

#Get Bios File Name (No Extension, used to create Log File)
$BiosLogFileName = $x[0].BaseName

#Set Command Arguments for Bios Update
$cmds = "/b=$BiosFileName /s /l=$LogPath\$BiosLogFileName"
Write-Host "cmds: $cmds"

#Update Bios
$Process = Start-Process $PSScriptRoot\Flash64W.exe  -ArgumentList $cmds -PassThru -wait

#Creates and Set TS Variable to be used to run additional steps if reboot requried.
if ($process.ExitCode -eq 2)
{ $tsenv.Value("SMSTS_BiosUpdateRebootRequired") = "True" }
else
{ $tsenv.Value("SMSTS_BiosUpdateRebootRequired") = "False" }
if ($process.ExitCode -eq 10)
{ $tsenv.Value("SMSTS_BiosUpdateBatteryCharge") = "True" }
else
{ $tsenv.Value("SMSTS_BiosUpdateBatteryCharge") = "False" }
Stop-Transcript

Can you try opening an administrator cmd prompt and typing tpm

You should see something like this: