Blocking a return air vent that is used is a big mistake. Many houses have heating or cooling problems because there is not enough return air. Most bedrooms could benefit from adding a vent to the bottom of the door like This One. It allows better inflow from the HVAC which is a recirculating system. Air can't get in if it can't get out. If this vent is connected to your HVAC, it is needed. Cutting a vent in the bottom of your faux fireplace will help, but return air vent size is important. My 1200 sf house has a 2-ton unit with a 20x24" return air. Two return vents suggest you have separate furnace and AC systems. The TV stand inhibited air movement, but it didn't stop it. You may be able to move these vents, but you should not just cover them over.

Thanks for the info. I definitely need to find a solution here.

Would love to know what you decided to do, im considering doing the same and totally forgot about this vent