no 4wd

so i posted on here a problem i was having with my 01 4runner but didnt get any answers. So I ended up taking it to the dealer to get it scanned , they said it was my add actuator which i already replaced with a new one , not oem .so i had them replace it $780.00 , now when i dropped it off i ask them if this was going to fix my 4wd they said oh yeah . So 6hrs later they call and tell me it did not fix it and that my 4wd ecu was fried, now if the ecu was fried how did they scan it to begin with? So right now i have the 4wd ecu out and apart . My question is can you tell if it is fried by looking at it . it looks perfectly fine to me

 

You can't tell. It might still communicate on the bus but maybe can't speak with the actuators.

I've "fried" circuits where you can't see what's wrong. You'd have to test it out at the component level and it could be a diode, or internal to an IC or a cold solder joint, etc.

 

I dont have a clue how to test it do you know if i can send them out to have tested if so where to