We have three service manuals covering the PLMV169 series, which you can download free:http://www.microwavedisplay.com/plmv169dcc_sm.pdfhttp://www.microwavedisplay.com/glmv169_plmv169_sm.pdfhttp://www.microwavedisplay.com/glmv169_plmv169_late_prod_sm.pdf
They're all pretty similar.
You can usually find parts from the Pros here
If not, contact Electrolux at the phone number on the front of the service manual.
It may be the C/T fuse (thermal fuse located above the magnetron) or the oven cavity thermal cutout, located on the top of the cavity.Accessing these two parts for testing and possible replacement will require you to remove the oven from the wall.
so, the installation instructions are very handy, and it's best to have
two people since the microwave can be heavy and awkward.
download Electrolux / Frigidaire owner's manuals and installation
It may also be that there was a power surge which damaged the control circuit board, activating the built-in surge protection.
This is not resettable. The circuit board has to be repaired. We do that for $39.95, details here
happy to help you with free
advice and we'd appreciate your thoughtful rating of our answer.