Dell inspiron i7-7500u 5767 fan not working properly.

Hello, I have a problem with my laptop - dell inspiron 5767 i7-7500u and its cooling system. I've took my laptop for cleaning and checked it myself - it's clean and from just looking I haven't noticed any problems with connections, yet the fan doesn't spin. The weirdest thing of all is that when I use it, sometimes it just randomly starts spinning and goes back to normal. I've reasearched a lot but I never got an anwser. Also the guys that I took the laptop to said that it worked fine for them. It's just so random and I can't figure this out. ALSO, earlier I used to go to the dell site and do diagnostics to my fan and it worked, the test needed to check if the fans were able to spin so it just started them, but now for whatever reason I can't even start the test. Sorry for all that confusion. I haven't really checked if updating bios would work but I'm a bit scared, if nothing else can work I will do it, but I'd rather not. Thank you