Not wholly sure you are right about this - I have the exact same problem on my Mk2 - is this one a Mk2? It wasn't stated - and I have got a 2A display board with the dimmer fix.

If you have a 2 display, then you can't actually fit the SMD cap as the dimmer controller chip is not on the back of the board.

I haven't got a solution to this: mine comes up with the display dim one time in about 20 starts in the car, and it either goes to full intensity at the end of boot (player startup) or when I press the down button to go to visuals.