By what you have done it still seams a signal proble via aerial/coaxal cable or connections.
Is the cable in the other room from the same aerial if not it could be the aerial.
If it is the same aerial try an extention cable into the room that does not work. If this work you still have a problem coaxal cable.
Did you replace the coaxal cable from the arial if not this could be the problem, also check the ends of the cable.