Random Shutdown Timer with powershell and no popup and hidden

Hi i try a cmd file or powershell file to shutdown a pc after a random time 20h and 24h with no popup message that the pc is shutting down in 10 minutes... and hidden

i try this

shutdown -r -t 86400 -c " "

Sekond way:

start powershell.exe -WindowStyle Hidden -Command "sleep 86400; shutdown -r -t 00"

but without random time between 20h and 24h