I have the same problem. New TCL Roku tv. During setup it connects to my WiFi just fine, strong signal, but when it does it's automatic software update I get error 003. Tried a manual software update using a USB thumb drive, followed the instructions to the letter, still get the same error.
I'm having the same issue with my 3 year TCL TV. Software updating issue just recently occurred.
Thanks for the posts.
For more troubleshooting steps regarding the issue you are experiencing, we would recommend taking a look at our Support page here: Software not updating on a streaming device
Please keep us posted what you find out and we will be able to assist you further.
Thanks,
Danny