Bricoleur

Update, I ve changed the melted big black Capacitor, two other small ones (C50 & C60) and the inductor which were near the Cap (orange line in picture attached) 
I ve turned on the inverter and:
- good news: voltage ramp up to 230V and stick to this voltage
- bad news the shortcircuit between AC input and output still exist. 
Follow the short circuit and it was not the relay, instead was the transistor in the card (holded by the four large metallic rope rising from the main board, in RED in the attached pic) 
I ve replaced the card (from my existing  burnt board) but the problem persist, infact I think (I am not sure) that the transistor on the new card burnt also once I ve turn on the inverter (no abnormal appearance but the transistor Source and drain well shorted out) 
Then I ve disconnect the card and turn on the inverter, It ran smoothly with 230v output without any error. 
Anyone knows what is the purpose of this card?