Unsure how to get Export-Csv to work for what I need

I have to rename a little over 100 computers in the warehouse where I work. My script is setup to delay the renaming process until a desired time and gets the computer names from a .csv file. The current date listed is just when I was planning on running the next test of the script before the full scale deployment.

$Credential=Get-Credential
$ComputerList = Import-Csv -Path '\\Shares\Scripts\computers.csv' 
$end = Get-Date "2024/06/11 06:00:00"

while ((Get-Date) -lt $end) {
    start-sleep 3600
}

foreach ($Computer in $ComputerList){
    Rename-Computer -ComputerName $Computer.oldname -NewName $Computer.newname -DomainCredential $Credential -Force -Restart
}

What I need help with, is using the Export-Csv function to generate a CSV file with a list of all machines that were offline or otherwise unable to be renamed. I was hoping to use the Write-Warning command to assist, but my understanding of powershell isn't quite high enough to work this out on my own. The computers are spread throughout a rather large warehouse and while I don't mind going out to them, I'd rather not have to touch every single machine to verify if the renaming was successful or not.

I've tested what I have so far, and it will skip over any computer listed in the .csv that is offline and continue down the list. I tested this with two machines while the first machine in the list was offline; hence, why I want to export what computers are offline or any error that's that are thrown if a renaming is unsuccessful. Bonus if I could have it add "Pass" / "Fail" as a third column in my existing .scv file.

Any assistance is greatly welcomed.

this generates\appends a CSV of only the failed renaming.

Should be enough of a base for you to change it to fit your purposes

$ComputerList = Import-Csv -Path '\\Shares\Scripts\computers.csv' 

$Credential = Get-Credential

# no reason to use a While
$EndSleep = Get-Date '2024/06/11 06:00:00'
$StartSleep = Get-Date 
Start-Sleep -Seconds ($EndSleep - $StartSleep).TotalSeconds

$FailureList = foreach ($Computer in $ComputerList) {
    # Splat the parameters, so it's easier to read    
    $Splat = @{
        ComputerName     = $Computer.oldname
        NewName          = $Computer.newname
        DomainCredential = $Credential
        Force            = $true
        Restart          = $true
        # PassThru returns a boolean whether or not the rename worked
        PassThru         = $true
        # ErrorAction Stop throws a breaking error if there is an error
        ErrorAction      = 'Stop'
    }

    try {
        $Result = Rename-Computer @Splat
        # if the rename failed cleanly, return an object with:
        # timestamp in UTC
        # the name of the computer that failed
        # and a generic reason
        if (-not $Result) { 
            [pscustomobject]@{
                TimestampUTC  = Get-Date -Format FileDateTimeUniversal
                ComputerName  = $Computer.oldname
                FailureReason = 'Rename-Computer did not succeed'
            } 
        }
    } 
    # if the rename failed throwing an error, catch it and return an object with:
    # timestamp in UTC
    # the name of the computer that failed
    # the error
    catch {
        [pscustomobject]@{
            TimestampUTC  = Get-Date -Format FileDateTimeUniversal
            ComputerName  = $Computer.oldname
            FailureReason = $_.Exception
        } 
    }
}

# Export failed renamings to a CSV, adding them to an existing one
$FailureList | Export-Csv -Path $CsvPath -NoTypeInformation -Append