You sure the device failed? For instance: if you try to test the Vgs before Vds with the Cgs input you closed the channel of the device and so you could measure a short circuit at the drain side. That doesnt mean the LDMOS failed of course
Hi. What is the maximum Vgs voltage ????... Maybe your multimeter is going over this limit !. I also think you have an ESD problem. I also would not measure the D-S with and open gate!. Not a smart plan.
The Vgs(Max) is abot 12V.My multimrter in Diode check position act as 1ma current source and reads the voltage across the p-n junction.This Problem happend only when the multimeter is in diode check position and 2Kohms Position.at other states (measuring larger resistors) there is no problem.i think that current source(1ma) cause the problem.