Just a couple suggestions that may help.

If the room has a forced air (heat/ac) vent, clean well (careful sheet metal is sharp)

Walls and trim should be primed and re-painted. As a painting vet one of the biggest mistakes I have seen a home owner do is use exterior paint inside, this requires ultraviolet(sun) to completely cure the paint where interior paint does not. You could have a residual on the walls/floor that is not curing(the smell), and or a chemical contamination of the walls/floor the concrete floor can be sealed with a “Block(TM)” type concrete sealant, and new carpet/flooring installed.

If you want to attempt something a little less expensive, and just time consuming…SCRUB with vinegar (less chance of a chemical reaction vs other cleaning chemicals and the acid in the vinegar MAY force the oils up and or cure the chemical residual) and then scrub again with water(floor and walls/ceiling) you may have a residual smell of vinegar, but it will go away. For the floor a wet/dry shop vac can help in the clean up of liquids, just remember to take the filter off when in use with liquids.

I hope this helps, and good luck with your project!

As always do more research, what kind of sealants/chemicals where used in the room, and call the manufacture for suggestions on decon/cleanup.

-PCK

use a concrete sealer or floor paint

You’ll need to seal it. A product like Kilz is both a stain and smell sealant, but you’ll need to ask the pros at your paint store if Kilz can be used on concrete.