I bought a solar cheap solar controller (10A) from Amazon, however, I done a little research before I bought. The model is not important (I don’t think, but you may say otherwise). So, I connected the battery first and the lights illuminated - all good! After about 10mins and prior to plugging in the solar the lights went out, followed by smoke coming from the box. I opened the box and no fuses were blown. However, it was clear a component on the board was blown or discoloured. The terminals +ve -ve we’re correct and the van was plugged in to the mains at the time which may or may not be a factor. The wiring was 12AWG and therefore fused at 30A. Does anyone have an idea what I’ve done wrong?