Let's assume the person is perfectly in the center of the room.
The mass of the earth would be pulling him in all directions. The forces would cause a pressure so high that he would likely be ripped apart.
Technically, though, the different sides of the earth would be pulling on each other, and this would exert such a huge force on the outside "walls" of the room that they would collapse, causing the masses of the earth squeeze the person. The only way that the person would not be crushed would be if the room was strong enough to resist breaking under the forces being exerted on it from all sides. This is impossible, however.
Another thing which I thought about was the high temperatures. Even if the room could withstand the pressure from the Earth, the temperature alone would be enough to evaporate the person. This seems to go along with the explosion theory, because the person would expand as he turns into a gas.
So, I have decided that the person is heated into a gas due to the intense pressure. At roughly the same time, (I dont know if the person would boil faster then the room would collapse) the room would cave in and pack together. The person would therefore have expanded into a gas and then crushed back into some sort of spherical human-fossil solid. However, if it took a long time for the person to be boiled into a gas, then I suppose he might just be crushed. Either way, it is likely that for both situations to occur nearly instantaneously. The end result though is that he is crushed. Although if the room was really durable, then I guess you would just be left with a room filled with a human-gas.
That's my theory. If you liked it, please pick me as the best answer.
Thanks for reading!!!