MLB issue? Fan spins up/down twice before booting.

I've noticed this trend with liquid damaged machine, and have it again with a machine in front of me. I'd like to know the root issue and how to properly fix it if possible.

After liquid contact, a logic board displays the following behavior:

• Press power button.
• Fan spins up and then down after a few seconds.
• Fan does the same again.
• Fan spins up, machine boots as usual and fan acts normally.

I've reset the SMC, checked that it happens in minimal configuration as well, and run all tests in the Apple Service Diagnostic (which this machine passes).

If I use it for a bit and then shut it down, and then boot again, oftentimes it will boot up without the above fan spin ups/spin downs. But if I leave it sit for awhile, it will do it again.

Does anyone have further insight?