2000 Volkswagen Beetle Dead Car

In trying to crank up my Bug, it would not turn over, despite trying to jump start it. I bought a new battery for it, and after installing, I opened the door - the dome light went on momentarily, and then it went completely dead, along with the rest of the car. I wasn't able to crank it - I even tried to jump start the new battery. The electrical hasn't worked at all, except for the clock, which comes on and then goes off upon a periodic clicking sound that can be heard from underneath the left dash. I checked the fuses on top of the battery - the metal ones appear fine and not corroded or burned, hard to tell with the 30 amp plastic covered ones, but when looking down into them, they look fine. A VW mechanic friend told me it's probably the new battery - that it was just a bad one that had been sitting on the shelf too long. I just want to ensure before I go to obtain a new battery, that it's not an electrical problem elsewhere, such as throttle module, ECM, etc. Your thoughts?