Cadence sensor dead after changing battery

This thread worked for me - after spending :45 minutes trying to figure it out.  The metal piece in the removable cap (light silver color) has to be lined-up correctly so that the long contactor "finger" lines-up with the + terminal contactor in the body of the sensor.  In my case the metal insert popped out of the removable cap with the battery - when I re-inserted it it was no longer correctly aligned.  Poor design - the metal pickup in the removable cap should be fixed to the cap so that It can't become misaligned.  Once I corrected alignment the sensor fired right up.

does the led flash green upon battery replacement in the sensor?  If not it's not powered - check the alignment of the metal piece in the removable battery cap - it has a long rectangular piece which rises to the top of the cap (when turned upside down) and this is what makes contact between the + battery terminal of the sensor and the battery holder (metal piece inside the cap).  The metal piece in the cap can become rotated out of alignment with the pickups in the body of the sensor - when this happens the +  side no longer makes contact and the sensor won't be powered.  Took me :45 minutes and finding this thread to fix it...