Chosen Solution
I found this cable broken, maybe I accidentally close it between the case… but apparently all is working without problem, I was thinking it is the cable of the right speaker, but it works well, so it can’t be. anyone know what cable is it and if I can find a replacement?
Follow the steps in this IFIXIT guide to replace the antenna unit: MacBook Pro 13" Unibody Mid 2012 Display Replacement not to worry we’re not going to replace the display only get to the part you’ll need to replace. Follow the steps to the end, once the display assembly is off you can then slide off the black clutch cover covering the antenna unit (its keyed to slide to the side). Between the hinge units is the antenna unit and here is the needed part: MacBook Pro 13" 2011 & 2012 iSight & Airport Antenna cable - Apple P/N: 818-1821. This part is not easily available from my normal suppliers I can only find it on eBay.
