Hi, im a newbi and i needed some help.

i have a audi a4 b7 s line, jumped in car the other day n tried to turn on the stereo and nothing happened. push the button in and no lights or powers up. took out the stereo and had a look at the fuse and that was ok. checked the fuse from the main box and eveything ok there. when i turn the lights on the stereo lights come on but does not power up. do i need a new HU?????

any help would be nice