I don't want to alarm you, but something causes the wires to overheat and melt the fuse box. Usually it is the alternator wire (heavy black one on the far right side. Do you have a repair or work order showing what was done?
The thermometer, okay, you me the outside ambient temperature display. What is happening? No display? Significantly off? The two can not be related, however in doing the work that was done, the plug could have been pulled loose from the sensor, below the battery in the front of the left front fendor, or a wire could have been pulled out. Did the one coincide with the other?