No sound (dummy output) on Inspiron 7000 using Ubuntu 16.04

I bought a Dell Inspiron 7000 notebook and after a couple days of use the sound just stopped working. Now it is showing an "Dummy Output".

I already tried all the answers in StackOverflow, like force reload alsa, kill pulse audio, make a lot of changes in the /etc/modprob/alsa-base.conf, update kernel, update DKMS...

Dell official support said they can't help because it is an unsupported OS, but I'm using the system that came with the equipment from the factory.

I hope someone could help me.

Solution 1:

Finally I found how to solve the problem. First I reverted all the changes in the system configurations, as installation of alsa, pulseaudio and config files, disabled the fast boot in BIOS options, then I updated the BIOS following this tutorial from DELL website and turned off the computer for some hours, now the sound is working.