12V DC iSensor LED Switch

I had previously (about ten years ago) purchased five of these iSensor devices. One has been in continuous use in a kitchen cupboard and has worked faultlessly. The others were to replace mechanically switched cupboard lights in bedroom built in cupboards. I only installed the last four about a month ago, and one failed during the night, failing to shut off the lights in a closed cupboard. The business from which I bought the systems had since closed and I was fortunate to find a supplier of teh identical product. The devices work admirably and I would suspect the IR transmitter has failed, and it does not sense the cupboard closed. The electronic sensors with LED lights is so far superior to mechanical switches and traditional lights that it does not bear comparison.