I recently bought a Bluetooth receiver from AliExpress (here) and used it successfully once with my Laptop. Afterwards I wanted to try using my phone to pair with the device, except it didn't show up in the list of ready devices. Assuming I needed to unpair my laptop I did that which resulted in none of my devices being able to pair since the device doesn't show up. Turning everything off and on again didn't do much except when I freshly start my PC for a few minutes I can see the device again but not connect; then it vanishes into undetectability (or so). The device only has one button and a LED and it seems like I can't get it into pairing mode, I can only turn it on and off.