S3 Bricked and I can't go into Download Mode

Hello Guys,

I wanted to install a custom ROM (Paranoid ROM 5.0)
After a successfull install my phone restarted. Now it's stuck at the Samsung Logo. I wanted to try to go into Download Mode, but my Volume Up Key doesn't work :( (To Confirm it) .
Now i ask you how to solve this problem. Is it possible to "press" keys in ADB? Or something like this??

Sorry for my bad english ^^

Thank you.