Xbox One S - No fan spin, missing PWM signal

I’m a newbie in board repairs, decided to try it on my friends broken Xbox One S. Any help would be appreciated. The console powers on with chime, after 1-2 seconds powers off also with chime. I have noticed that fan does not spin at all, not even typical quarter spin, when connecting console to power. Checked with another fan, nothing changed. I have checked voltages on Fan connector. Going from pin closest to front edge of motherboard, Ground, 12v, 2.85v, 0v.) It seams like the console does not send PWM signal? I have checked on my Fat model, there should be about 1v on startup. What component is responsible for that? I tried to trace this pin back, but unfortunately it seemingly disappears right away.
Thanks for any answer!