could be an protector device tvs ... tds ... or simply an diode as you say, can you give us the model, a brand ... we see only the pcb
If this part is shorted out, if so you could remove it and see if there any voltages on the pads ac or dc
![Huh? ???](https://www.eevblog.com/forum/Smileys/default/huh.gif)
maybe the meter will start ??