HP250 G4 laptop, error 90B?

Question

Iron

I have an HP250 G4 laptop with serial number: CND5400VN5 and product code: N0Y20ES#ACB The
laptop gives error 90B, which indicates a malfunction in the cooling system. But this model has a passive cooling system. What was done:
1. Replacing the thermal paste
2. Updating the BIOS from F.11 to F.23
3. Forced hardware reset (poweroff button 15 sec)
4. In Bios, set the fan always on parameter to disabled
Where to dig?