Total Brake Failure 2005 Passat TDI

This morning I installed a new VW dealer battery into my Passat. The car started as expected; however, I had a new, and still have, a steady thumping noise coming from the engine compartment (sounds like passenger side) that rises and falls with engine RPMs as soon as I start the engine. That sound was definitely not there before the battery replacement 1 day ago. Immediately after I replaced the battery I drove the car slowly down through my parking garage and at about 250 yards, the brakes failed completely. I bumped the car into neutral and pulled the handbrake slowly and came to a stop. The camshaft was replaced less than 20,000 miles ago. The maintenance is impeccable and done at the dealer. I don't cut corners. Any thoughts on what the thumping could be and could it be related to the brake failure. The brake pedal is like pressing on a brick; there is no travel in the pedal. Thanks again for any comments or suggestions.

check the vaccum hose that leads from firewall to brake booster. you might have broken or unpluged it when you changed the battery. common mistake

Yes, that was the issue. I knocked it off during installation. I simply plugged it back in at the firewall. Thanks!

You had a brake assist failure, not a brake failure. Pressing the brake pedal will still stop the car, though a *lot* of force might be required.

-J