No fans are running

Recently, I turned on the printer and noticed that none of the fans are working. No power supply fan, no hot end or motherboard one.
Other than that, the printer is working (printing)
Any suggestions?

A new transferboard could be the solution maybe some traces are burned out at your transferboard (price new transferboard abt 20 euro)
I had that problem (no fan) when I accidentically shortcircuited my one by soldering while power was still on of my CR10S Pro.

while replacing I noticed a burned out trace on my transferboard. (the one that connects the fan wires)