Welcome to the SeeMeCNC Community

I feel a bit like an idiot here. I have a Rostock Max V2 with an HE280 Hot End. I wanted to clean some of the gook off the hot nozzle. Using a small wire brush I think I managed to jump power from the heater cartridge to the Thermister. They was a quick spark than everything went dead. No lights in the board, nothing on the display and no indicators on the hot end. Tried unplugging and resetting the board nothing, I noticed there is a fuse on the board but it looks fine.

I don't even now where to start or what will need to be replaced. Does anyone know how bad this is?

Thanks,

I would start by checking the Power Supply voltage, no power supply voltage check wall outlet. Then see it the voltage make it to the controller.
Never trust looking to see if a fuses looks good, always measure fuse with a continuity tester, and Power with a multi-meter.

Worse case scenario would be the the controller, and thermister are dead.
Unless you know how to troubleshoot to component level. Then I would suspect Fuse, Heater Mosfet, controller regulator chip and thermister.

There are three fuses, two of which are very small, and have no visual indicator. The one that's visible is the heated bed fuse. The others are just below the power entry point, and just inboard of it, under a capacitor. It's most likely you've killed one of them. they are relatively available. https://www.seemecnc.com/products/5-amp ... -for-rambo

It was the fuse! Back in business - thanks all