|Is this a laptop?|
When you fixed the fan did you clean all of the cooling vents and areas where dust accumulates?
Try powering down the computer and remove all power sources such as battery and power connector.
Once all of the power sources have been removed press and hold the power button for 20 seconds then release.
This will flush any charge that the capacitors are holding.
Reassemble the computer by attaching the power sources and power on.
Does the error message still display?