My Samsung model EP-PN920 wireless charger (the flat hockey puck looking thing) worked flawlessly for two years, reliably charging my Samsung Note 5 phone from Jan, 2016 to Jan, 2018. Then I began experiencing the blinking blue light and the cessation of charging. I thought that maybe the problem was caused by the Jan 1, 2018 software update, so I began charging the phone via USB, and waited for the next update….which arrived, but the problem remained. I removed the fairly thick rubber cover I use (the liner from an OtterBox Commuter Cell Phone Case) from the phone, and the wireless charging problem went away. Hmmm, seems like there’s something impeding the current between the charger and the phone. What could have changed, I wondered. Unable to think of anything else, and doubting it would make a difference, I used a damp cloth to wipe the top of the charger, dried it, and waited for about 15 minutes. Then I put the rubber Otter case liner back on the phone, put the phone on the charger, and it’s worked great ever since! (I guess there must have been two years’ worth of dust on the charger, though the shiny white surface hid it well….ouch, I’m a embarrassingly lousy housekeeper, lol.)