If there is no power at all to the POS or printer, first check whether the power connection on the power adapter is loose or disconnected.

Please check if the power adapter has a green light and the power cable is securely connected.

Then, check if the connection at the POS power socket and the wall socket is also secure.

If the POS power adapter has a green light, please unplug it to isolate the POS from the power source and leave it disconnected for at least 10 minutes. Then reconnect the power and try again.