Do a hard reset by using the small power button to turn it off and then, while holding the surround mode buttons in, use the same power button to turn it on. Keep pressing the mode buttons for at least 5 seconds and release them. You'll see the screen light up most of the LCD segments and it will finish resetting shortly after. Try the update again. If you still can't get it to work, do a connection speed test using that cable connected to a computer. If that's normal, reset the network card by turning the receiver off the same way as before. Then, press the Up and Down buttons on the circular Up/Down/Right/Left set and turn it on, holding them in for about 5 seconds before releasing them. Once it's done resetting, go to Menu, Manual Setup, Networking and verify that it has an IP address. If it does, do the update again.
If you did the whole setup and want to avoid doing it again, you can save the configuration as long as the receiver is connecting to the network. In your case, do the network reset first and see if it works. If not, write all of your settings down and reset the processor.