How do you determine the value of a burnt resistor?

Carefully scrap the insulating material off along a straight line on the resistor body using a pen knife until you can see the spiral track of the resistive material.

Chances are you can still measure some resistance, using either end of the connection lead and a pointed pin, pricking at the spiral track.

Starts from one end and advance on each spiral track until you have found an open circuit. Record the resistance before this happens. Do the other end using the same method.

Add the resistance found in both cases and adds 10% more. This will give you the approximate resistance of the original resistor.

This method often works because resistor burns open in one spot only.