Today I fixed a long-standing fault in my Kenwood AV amplifier. I was sure the remote control was faulty, but then I found that there is a known common fault with Kenwoods: the infrared sensor (behind the right end of the display viewed from front) develops a dry-joint caused by thermal movement of its 3 legs. The cure is to take the lid off the case and re-solder the sensor legs. You can prove the fault by poking the area with your finger, whereupon the R/C will probably start working.