Inspiron 27 7720 All-in-One Fans max speed

Hello all,

I am having the following problem. One day my computer was on and suddenly we lost power in the house which is why the computer suddenly lost power. After restarting, I had to fill in the bitlocker code to get back on my desktop. Since then the fan goes full throttle from the moment I turn on the pc. I also noticed that the desktop was now starting in manufacturing mode and was missing the service tag. When I pressed alt f to go back into normal running mode, the desktop made a high pitched noise and immediately shut off. Since then, I have updated my BIOS using an external usb as doing it from the local hard drive always gave an error. After multiple failed attempts I first filled in the service tag, then pressed alt f and then it did go into normal running mode. Afterwards I tried to reinstall the newest version of the BIOS with an external usb and it worked this time. I have also done a complete full power/EC reset (unplugged, held power button 40 seconds) and still when the desktop is running, the fans are at full speed. When I tried support assist, there seemed only one problem and that is that it is not able to search for new updates but the hardware seems fine. I can hear it testing the fans as they go all the way down and then back to full throtlle. I feel that they are in fail safe mode but cant figure out how to fix them. 

PS correct me if i am wrong but i dont believe that it is the CMOS battery as date is set correctly and the pc can now start normally.