The following work should not be carried out without electrical knowledge. I'm not responsible for any damage caused. Everything you do is done at your own risk.
Unplug the power cord before opening the printer.
The holder attaches to the inside of the Y-axis limit switch holes. You have to remove the limit switch beforehand. The existing screws must be replaced with longer ones.
If you control the printer via Octoprint you can use the two plugins PSU Control and PSU Control - Shelly to switch the printer on and off.
The author hasn't provided the model origin yet.