My heated bed has been overheating-- as soon as I plug in the printer it starts heating up and doesn't stop until I unplug it. I had it for a few weeks before this started. Any ideas what it could be? Possibly related: the transistor above the row of six connectors on the control board seems to have overheated and melted the connectors a tiny bit (see pictures).by Moriabbey - Prusa i3 and variants