This script that will send a reboot command to a remote computer. It will then monitor for it to go offline and then come back online. Optionally, you can have it monitor for a service to return to running.

# The remote computer to reboot
$computer = 'YourComputer'
# the name of a service to check for after reboot
$Service  = 'WinRM'

# send reboot command to remote computer
Restart-Computer -ComputerName $computer -Force -ErrorAction Stop

# ping computer every second until it goes offline
do{
    $test = Test-Connection -ComputerName $Computer -Count 1 -Quiet
    Start-Sleep -s 1
}while($test -ne $false)

# ping computer every 10 seconds until it comes back online
while($test -eq $false){
    $test = Test-Connection -ComputerName $Computer -Count 1 -Quiet
    Start-Sleep -s 10
}

# wait for service to show running
if(-not [string]::IsNullOrEmpty($Service)){
    do{
        $test = Get-Service -Name  -ComputerName $Computer -ErrorAction SilentlyContinue
        Start-Sleep -s 10
    }while($test.Status -ne 'Running')
}