I have an AQUABOT control board that is used to power a pool robot. The robot became bogged down while cleaning debris and overloaded the control board but the fuse did not blow. Instead, the Viper12 IC (red circle) blew along with a Zener diode on the bottom of the board. I replaced both but I am not getting the 29v output (green arrows) for the robot. I tried replacing the Zener (unidentifiable from damage) with aTL431, that didn't work so now I have a Y11 Zener and still 0v. I'm not sure what I missed. All diodes/resistors tested good as did the double diode. No schematic seems to be available.

I'm try to determine why I am not getting the 29v & hoping someone can offer me some insight as to what I should replace, check, test, ect. This board also powers a front panel that has a timer and a few other functions, that part does turn on. The power switch is connected to the board with 4 pin ribbon connector labeled 'key', '5v', 'grnd', and led. The front panel is also connected by a very short ribbon connector.

 

So, you did some component replacement But did not receive any fruitful results. Still, the PCB is faulty. I suggest you run a short circuit test. You can see the modern PCB testing strategies here: https://www.pcbway.com/blog/2/Modern_PCB_testing_strategies.html
Also, Trace the circuit path from the Viper12 IC to the 29V output point. try to see if there is a broken trace somewhere in the PCB.