Confused about what you said...
PA4010 has no Wi-Fi function...How did you upgrade it wirelessly?
Are you talking about WPA4220? Which one in the kit has no lights?

I connected to the WIFI router that was connected to the PA4010 by ethernet.

The firmware payload was thus send over wifi, via the router, over ethernet to the PA4010

To upgrade the firmware, you have to connect PC and PA4010, and then run the utility on the PC to upgrade it. How did you upgrade when it is connected to your router? :confused:
Anyway, maybe it is NOT caused by firmware upgrade. Since it has no lights any more, it should be faulty. Is it still under warranty? Contact your retailer.

Well, the TL-PA4010 has three LED-indicators :D
I bought it in a kit (Ethernet PA4010 and WIFI/Ethernet WPA4220).

I had the same problem. I made a firmware upgrade with the correct firmware over the network. The upgrade seamed to work, but there was a "failed" message at the last step. It's my job to work with small embedded computers, I think I didn't make a mistake.
After a reboot, the PA4010 was dead. The case can't be opened without cutting it off and you lose the warranty if you do it.
I did it, but found no console port to use for a serial rescue console - and put it in the dustbin for electronic trash.
I bought a better version at ebay, with AC-Power pass through and two ethernet ports.

Next time - no firmware upgrade :D

The same here. I think these adapters should have protection of the firmware update process. Unfortunately I lost a PA4010 unit trying update a WPA4220, because the software is very confusing and not clearly show which drive is which. I think the software should have recognized the incorrect model and alert before starting the process, like any standard router in the market.

Only thing that kept running is the LAN port. The LED on my router shows active communication. Good situation to enter in the service mode, if there was... :rolleyes:

RESULT: Update your powerline and win a paperweight.

Update this powerline? Nevermore!