tiida 07 starting issues

hi guys
im having issues with my nissan tiida 07 hatchback.
So the AC wasnt working only blowing hot air, so i checked the fuses and found the found it blown, replaced with new one and it was working fine. ran it for the day and when i got home that evening it was blown again. so replaced it again.
this time i left the car on with the AC running then I had a burning smell coming from the AC ducts. after that the car switched off. when i tried starting it again, it was cranking but not switching on. called a mechanic and he checked if there was spark, and there was none. called an auto electrician and checked all fuses and all was ok. after checking other stuff we noticed that the radiator fan is on as soon as you put it on ignition and the check engine light doesnt come on at all. please help!!! what can possibly be the issue??