How do you fix your radio in your 2000 Volvo s40?

-- Thoroughly identify all of the radio's functions that are operating normally
and those functions that have failed.

-- With the help of those two lists as guides, identify the radio's subsystem that has
ceased normal operation and, if possible, the component or components within that
subsystem that have failed.

-- Repair or replace the failed component/s, or the faulted subsystem, or the radio itself,
according as is appropriate after estimating the cost and time to repair or replace in the
specific case of the root cause identified.