Mini appears dead; Fuse to replace?

Today as we were trying to clean some filament off the print head of one of our Lulzbot Minis, metal tweezers made contact with the two red shielded red wires that go to the heater cartridge (or something in that vicinity). The printer was on and connected when this happened.
We believe the wires to the heater cartridge are still connected to the connector housing and were not damaged. However, now in Cura we are unable to connect to the printer. Cura does sense that there is a USB device, but returns the error message, “Can’t connect to printer.” The Power switch light comes on, but no fan. I also noticed on our other mini that I can see a small LED light shining in the space next to the USB connector when it is turned on. I don’t see one shining on the printer that is not working.

Serial number KT-PR0035NA-10940

Does the Lulzbot mini have a replaceable fuse? Any other ideas of what the problem might be?

Yes, the Mini has three fuses and you most likely blew one of them. It has three standard automotive blade style fuses on the main circuit board. One blue 20 amp fuse and two brown 5 amp fuses. I think it’s one of the 5 amp ones that blows with a heater short. It’s very likely the fuse did its job and blew and protected the board from any further damage.

The behavior of Cura seeing the printer but not being able to connect is consistent with a blown fuse. The USB interface chip is actually powered from the connected computer so that’s why Cura can see that the printer is connected, but the blown fuse prevents the main controller chip from powering on so that’s why you can’t connect to it.

If you have and know how to use a multimeter you can pull and check the fuses to see if they are blown. If you don’t have a meter you can sometimes see which fuse is blown just by pulling them out and looking to see if the metal link inside the plastic, between the two terminals, is blown. Or just buy a few of each kind and replace them one at a time until it works again. You should be able to buy fuses anywhere that sells automotive blade style fuses.