these web links r links to images of wat to do, should make it easier to figure out wat to do
Press this switch
Press this wall then get yellow key
kill badguys outside room
then go down corridor till u get to the switch, wen u press it it should light from green to red, then turn around and head back to the elevator u came in by. go into the area with the 4 chain metal boxed in areas, and go through the door on your right to get to the red key.
(the uploaded images may be a bit dark but should be readable)