GX280 Small Mini Tower Startup Problems

I have 3 virtually identical Dell GX280 small mini tower systems. They all seem to have the problem where upon startup, the fan spins at high speed and sounds like a jet engine and nothing else works and that means the machine does not even boot or run  POST, let alone starting up windows.

There is no question whatever that this problem greatly depends upon whether or not there is humidity.

If I put a hair dryer on the motherboard for about 5 seconds, the problem goes away.

There must be a humidity sensor somewhere that I can bypass. Where is it and how do I bypass it?