L button always on after cleaning

The L button on my DSi didn't work. Following the advice of the forums I disassembled the console and cleaned the micro switches with cotton and alcohol. After mounting the console the L button is always pressed. No matter what I do it won't turn off.

I have disassembled the console again and I have checked the continuity with a multimeter and what I have seen is that the switch is fine and that there are no strange continuities in the ribbon connector either. I have been able to see that the pin corresponding to the L button is 25 and measuring strange continuities on the motherboard I have not observed anything strange either. But when I mount the console and turn it on, the L button is still on.