(https://surplustronics.co.nz/products/7589-step-up-power-module-dc-dc-boost-converter)

my power supply is 12v 12.5A, and the maximum input current is 4A. to solve this, I have a 1.5ohm resistor in parallel with the converter. (see attached diagram) when I try adjust the voltage, nothing happens, and so far i have burnt out 2 boards. can anyone tell me how to use one of these? any help would be much appreciated.

-Rob