Unable to connect sharepoint online site collection using powershell

Lokeswar_Reddy 

This is expected error since you need to pass the Admin site URL (Tenant site url) for Connect-SPOService.

You can check this post : https://docs.microsoft.com/en-us/powershell/module/sharepoint-online/connect-sposervice

Connect-SPOService -url https://TenantName-admin.sharepoint.com

As you know, the Connect-SPOService cmdlet is belong to SPO Management module. For List items update, you have to either use CSOM based script or PnP PowerShell commands.

$SiteUrl = "https://crescent.sharepoint.com/sites/marketing"
$ListName = "CustomerContacts"
$CSVPath = "C:\temp\CustomerContacts.csv"
 
#Get CSV file content
$CSVData = Import-CsV -Path $CSVPath
 
#Connect to site
Connect-PnPOnline $SiteUrl -Interactive
 
#Iterate through each Row in the CSV and import as list item SPO List
ForEach ($Row in $CSVData)
{
#Add List Items
Add-PnPListItem -List $ListName -Values @{
"CustomerName" = $($Row.CustomerName);
"Email" = $($Row.Email); 
"Mobile" = $($Row.Mobile);
};
}