Do you have a speaker to connect to the motherboard?(The one that beeps post codes, its usually shipped with the mobo/case.) If so, try to boot it without the ram or CPU. If it won’t beep any fault code, then it should be a clear indication that the motherboard is dead.

At my work(meat processing plant), we had a standard PC(dell optiplex to be exact) in a small kiosk in the middle of the hall. Inside, there was a looooooot of moisture due to condensation and leakage(the halls are sprayed with detergents and water after every shift).

The power supply died twice and the motherboard once, it was in a timestamp of 3 years

So basically yeah, the moisture is able to damage a computer, but if the room isnt damp 24/7, then it shouldn’t be a VERY likely scenario.

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If you can, move the computer somewhere else just to be 100% sure.