Radio display dim or no backlight

Hi everybody,

I bought my '96 318is 85k about a year ago. It's a great car, love to
drive it. It came with a standard Alpine radio system fitted into these
cars after '96. The backlight in the radio has never been working
eversince I bought the car. But occasionally it would go into a dim
mode. Once, a few month ago, I was driving on a highway and for no
reason it illuminated all the way up, which means that bulbs/leds are
working fine and aren't burned out. But it's never worked since. There
must be some electrical issue.

I was browsing through this NG and found many people having the same
problem but never found any do-it-yourself solution. Does any of you
have any experience and advice in fixing that? Not necessarily take it
to the shop.

Any help would be appreciated!!
Thanks,
Piotr