Where are the SMC sensors located?

SMC uses quite a few sensors so identifying them all won't really help you here.

Liquid damaged systems are always difficult to fix as depending on what was spilled may leave corrosive deposits or short out logic circuits.

Basically this is a bath job! You'll need to strip-down the system and clean up the spillage and/or neutralize any acids or bases that are present. Using distilled water (not tap!!) we wash down the disassembled parts washing away and sugars or salts as well as neutralize the acids or bases. Then we wash the parts down again with a high grade of Isopropyl alcohol (85% or better) to wicket the water and to remove any illd or greases that maybe present on the logic board. Often we need to use a bit of scrubbing being careful not to lift any of the tiny SMT components. Then we lets things drive out and reassemble if needed replace parts that are too far gone or to difficult to clean like the upper case.

Do you know what was spilled and when? Also was it a lot or just a little?