Start-FullPasswordSync.ps1

# run on server with EntraConnect installed

# name of on-premises AD EntraConnect connector
$adConnector  = "varunagroup.de"

# name of Entra ID EntraConnect connector
$aadConnector = "varunagroup.onmicrosoft.com - AAD"

# do the magic stuff
Import-Module adsync
$c = Get-ADSyncConnector -Name $adConnector
$p = New-Object Microsoft.IdentityManagement.PowerShell.ObjectModel.ConfigurationParameter "Microsoft.Synchronize.ForceFullPasswordSync", String, ConnectorGlobal, $null, $null, $null
$p.Value = 1
$c.GlobalParameters.Remove($p.Name)
$c.GlobalParameters.Add($p)
$c = Add-ADSyncConnector -Connector $c

# have you turned it off andon again
Set-ADSyncAADPasswordSyncConfiguration -SourceConnector $adConnector -TargetConnector $aadConnector -Enable $false
Set-ADSyncAADPasswordSyncConfiguration -SourceConnector $adConnector -TargetConnector $aadConnector -Enable $true