Left Fan at full speed even when computer is switched off

Hi community,

One day after a long storage time I switched on my MacBook Pro 13" 2020 (A2251) and the left fan was on at full blast all the time — even with the machine switched off. The fan (usually 8881 rpm) only switches off when the machine goes completely out of battery.

I tried SMC and PRAM reset to no avail, reinstalling the operating system didn't help, etc etc. I downloaded MacsFanControl but I can't reduce the speed or switch off the fan using the software (btw, right fan is ok, usually at 0 rpm—maybe to compensate—but can be controlled ok using MacsFanControl). The laptop just went out of warranty and I would like to avoid bringing it in for repair.

I am no expert but it feels like there must be some physical component (like a transistor) that has some issue. There was no water spillage whatsoever (not that I remember of at least), I just left the computer stored in a drawer inside its laptop case (protected from dust) for a few months while on parental leave. However, the computer was stored under a heavy pile of paper sheets (maybe 3-4 pounds). I'm unsure this could have caused the problem.

Could a fan replacement help? I am not convinced of this option because the fan is actually working, what is not working is the control of the fan speed. Any input is welcome!!

Thanks in advance you all,

sil