So, the receiver is dead.
The slightly interesting part of this is, I have a PINE64 with an i2c temp/humidity sensor, being monitored/logged over SNMP. The temp sensor is sitting on the receiver and you can easily correlate when the receiver is on or off by the readings.
Well, you can pretty much see when things started to go haywire.
(don't mind the bumpiness toward the right, the older data is averaged.)
I guess I should have tagged #pine64 for this thread.
The extra sucky part, is that on top of the receiver dying, when I went to wake my workstation up, the USB connector finally gave up the ghost.
It's my nice mechanical keyboard with hall-effect switches, too.
I'm think gonna have to attempt soldering a new USB port.