I lost a receiver last week. It flaked out on on me while messing with steering throw on the bench. After fiddling with plugs and binding for a while, it randomly started working again, and was fine on race night. Then it did the same thing again when I was messing with the wiring earlier this week, except it didn't come back. Now, it's a spektrum, so it could have just died. It wouldn't be the first time that's happened to anyone.
But, it occurred to me that before it flaked out the first time, I had done a firmware update on the ESC. While it was updating, I noticed the RPMs on my fan that's connected to the receiver were much higher than usual with my BEC set to 6v. That would indicate that the voltage was higher during the update.
So for safety sake, it might be best to unplug the ESC from your receiver before doing a firmware update.
-Mike