2010 Passat 2.0 I killed the battery by trying to get it to start at first crank crank turn on stay on for 2 seconds and then die not it won't even do that I don't know if it's the fuel pump

Hello, You have two fuel pumps. One in the tank, and a high pressure mechanical pump on the engine. The high pressure fuel pump is ran off of the intake camshaft at the back of the engine (nearest transmission). You have to make sure the fuel pump is running when you open the door. It should run for several seconds, then turn off. It should not restart until the engine is on. The high pressure fuel pump runs only when the engine is turning, and is necessary for the direct injection. You can use a fuel pressure gauge or a diagnostic scanner to determine output, but I'll tell you, the high pressure fuel pump (HPFP) dies on these cars... a lot. Test before you replace, and scan it for trouble codes before you dig into a diagnostic path.