How to tell if an IGBT is latched or broken?
Turn power off (and if the IGBT is not soldered in, remove it), and measure resistances between gate, emitter and collector (or use the meter's diode function, if it shows a short as zero).  Measure each pair in both directions.  If the emitter-collector pair shows short (0 ohms or 0 volts) in both directions, you have blown the IGBT.  If the gate-emitter and/or gate-collector also shows short in both directions, you've really blown the IGBT.  Even in-circuit it shouldn't show short in every direction, so that's a pretty good indication that it's fried.