PowRoku is a nifty little PowerShell module to help automate your Roku(s).

It is built atop the Roku External Control Protocol.

You can use PowRoku to control Roku devices and Roku TVs.

Assuming you have a Roku TV, and it's on, use this to try it out:

Find-Roku                 # Find your Rokus

Find-Roku | Get-Roku -App # Get all of the Apps on each Roku

Find-Roku | Get-Roku -ActiveApp # Get the Active App on each Roku

Find-Roku | Stop-Roku     # Turn your Roku TV off (only works for Rokus which support PowerOff)

# Turn up the volume
Send-Roku -Method POST -Data '' -Command Keypress/VolumeUp

Find-Roku | 
    Get-Roku -App | 
    Where-Object { $_.Name -eq 'Netflix' } | 
    Start-Roku

Start-Roku -MacAddress $myRokuMac # Send a Wake-on-Lan to your Roku's MACAddress