New starter but still no start. 01 audi a8

With all this engine work -- did you verify the engine is turning when putting a breaker bar and socket on the crankshaft? If the engine turns freely, then there must be a problem with the starter or cabling to the starter. Or the battery, or corrosion at the cables. Start by checking for engine rotation, then battery state of charge, then cabling, connections, and corrosion.