Completely dead
 

Hi, i am new around here, but i have big problem with my volvo s80 2001 diesel.
Everything worked fine, until a very rainy day, some lights poped up such as abs, engine, traction control and battery light flickered. Took battery negative off for about 5 minutes and everything started to work fine, but net morning engine wouldnt even turn over. Replaced battery and tried again, but even worse. now only thing that works is ac blower, radio and engine light on instrument cluster. Even central locking, power windows and light switch wont work, everything is dead. When i try to start the car, it just clicks and instrument cluster wont work either, except engine light. Diagnostic guy said theres only immobilizer fault. Help me please, dont know what to do!

Thank you!