Code P1B77, HEV Hybrid system check?

Get my vehicle listed above out from dealership from recall last Wednesday ( 4 days ago), they replaced hybrid battery and power relay assembly in the back of the car, it drove fine back home but after 4 days this Sunday car is showing me the HEV Hybrid check fault, trying to read the code with the OBD II doesn't give me anything, or sometimes was giving me P1B77 code which is related to the 125A fuse in the back which is connecting the battery to the car. I replaced it and checked everything properly (power relay assembly) and everything like new like it should be (after checking it with Multimeter and etc.). So right now, I'm still having the same issue, my car cannot ne started and after "system check" wording on the dash panel I'm getting faulty codes. I tore down the HPCU which is the Power Inverter of the car, and after opening it up, it smelled like something burning in there! After checking everything visually, I didn't find anything. I'm currently on the stage to check it with multimeter. So, my question is, can someone guide me to where should I look in order to fix the inverter myself, as I think it's a really minor problem in there and the new one costs a lot of money. Please help!