Is there a method of figuring out whether or not my stepper drivers are dead?
Most surefire way to tell if your drivers work is to wire them up CORRECTLY and try them out.  You should not be frying them if you have the correct setup (including current limit) for your conditions.  That said, conditions include your heat sink install and the environmental temperature.
The usual gotchas:

Note that DRV8825 and A4988s may have different pin locations so be sure to orient them correctly (check their EN pin location) if using a shield.
Also note that the gains from the voltage to the current limits will be different for the different model #s.  Be sure to use an appropriately sized screw driver and attach the meter to the screw driver as you turn to adjust the current limit.