2010 Jetta TDI popping sound from radio

[NINFan]

I started my 2010 Jetta TDI the other day and started to drive away. After a couple of minutes, the radio just stopped working, the screen went black, and a loud popping sound started at about 2/sec. I shut the car off and waited a minute, but the sound continued - even with the key out. I had to get my son to school, so I couldn't do anything, so just drove it. On my way to work, it just stopped popping. I turned the radio on again and it started working. After a few minutes it stopped working and started popping again. Got to work, left the car with the popping in the lot. Came out 4 hours later and it was still popping. Took the fuse out and it stopped finally. Put the fuse back in this morning (24 hrs later) and it's now completely dead.

Any ideas?

[NINFan]

Update: I took the radio out the other day. The fuse in the back is good, but I realized that even the lights on the dial are out. Is there another fuse somewhere? (Besides the one on the radio and the one in the fuse block under the hood.) I'm beginning to think it's the amp under the passenger seat and not the radio itself. VW replaced the amp under warranty when the car was new because it was freaking out when the iPhone was plugged in.
I also had to replace the battery the other day. I'm concerned that it's not a coincidence. Thinking that the radio issue is slow draining the battery - especially because when the problem surfaced, the radio was still popping with the key out.