@@stefan-norge Thanks for the response. I'll take a look again. I found something from them but it was listed as FCX24 so I wasn't sure if it would still work for the FCX18.
I got the solution from Nick Abbotts (Facebook groupe): just switch the wire of the black back light plug from the middle position to the outside position. Gets easy: just lift the pin of the wire in the black plug and you can easily slide it out of the middle position and slide it back in the outside position.