Radio & Nav sound issues

I know there have been quite a few posts on radio issues but I have not seen a post that matches the particulars of my problem. I have a 98 e39 528i with radio and navigation display, no DSP and old phone that is not connected. The sound quit working several days ago. All lights were on and all functions appear to work. I don't use the nav because I don't have a disk for it. I have tried some of the tips in the forums without success. Pulled the head unit out, re-seeded all plugs, no success. Checked and re-seeded all fuses in glove box and trunk, no success. Charged battery (left headlights on by mistake) and unplugged negative terminal. When I reconnected terminal no sound. Programmed display for clock and calender, pushed the orange tape looking button on display, and I had sound! Sound quit shortly thereafter however. Not sure what the next step I should take is. Do I check the amp plugs in the left rear of trunk? Drink Jack Daniels until I pass out? Any help would be great!!

Sounds like a bad amp. disconnect the battery, discharge the car, reconnect battery if you get sound for a few min. the amp is bad 9/10 times.

where can i find a disk for nav need maps of aust?????


please help