Blew up 5V Power Supply and ESC

Hi All, currently I’ve a custom 20V power supply for the blueROV. And I’m using your 400V Topside power supply. Having issues of 20V PSU tripping when running thrusters in air, so we put a schottky diode (DSS 2x101-015A) in-line of the +ve side of PSU to prevent tripping.

It seems to work initially, but we had 2 occurrences when we turned on the PSU, we blew up the 5V 6A power supply and all the ESC’s!
Is it something that I’ve done wrong? Would be much appreciated if someone can help!