Rear view mirror auto dim not working anymore

    I don't know what to try to fix the auto-dimming to work again. I have cleaned both sensors... I observed that (in daytime)  by blocking the ambient sensor- the one at the back of the mirror - with the finger for a few good seconds, the warning green led in the front reduces the light intensity meaning that it senses when is night so its working.   Then using the phone torch on the glare sensor- the one adjacent To on/off button and nothing happens, no dim 😕. 
 Have anyone had this problem?