I'm assuming you've performed the diode test in both directions and confirmed it's a short both ways, and compared it against the diodes in the same location on one of the working ESCs to confirm they test differently than they should.
If you're unable to find the datasheet for that exact part, it's probably not too difficult to source a comparable diode since you have working ESCs and other parts of that same part number on the same ESC. You can test the forward voltage drop of working diodes of the same part number to get a feel for if it's a standard rectifier diode or if it's maybe a Schottky diode. There appears to be a small value resistor (0.004 ohm) in series with each of the diodes and you know the peak battery voltage which means you should be able to determine at least how much current the replacement would need to be rated for, then derate that by 25-50% to gain some margin, then track one down with that same footprint.
With that low of a series resistor I would doubt that it's a Zener diode. It seems more likely to be used as a reverse protection or current monitor arrangement.
Best of luck!
-Rod
