Try changing the router's SSID to something else. Make it SIMPLE, and keep it to say 8 alphanumerics. There is no security risk in SSID selection but changing it will force the TV to stop trying it's old connection.
What is this "passcode"? Let's hope you configured the router to first, defaults, then change the SSID, then lock it down with WPA2 AES personal security and a password. When I read passcode that could be WEP that is busted broken and trouble.
I purchased a Samsung UN46EH5300FXZA Version TH02 46-Inch 1080p 60Hz LED HDTV in March 2013, and it has generally worked fine for the past 11 months. However, this week, it will no longer connect to the router. This is a problem because since we don't have cable, it means we cannot connect to Amazon, Netflix, etc. to watch any programs. Again, it has worked just fine in the past, all other devices (phones, iPad, computer) connect to wifi without issue. The TV sees the wifi, I've typed in the passcode 20+ times, it waits and waits, and then says unable to connect, showing IP addresses as all 0's. Issue with TV? Firmware update needed? Wifi card bad? I've also tried resetting the TV to its original settings, but that did not help. For what it's worth, we have Xfinity internet, using their standard modem connected to a Linksys router. I also tried resetting both the modem and router - no luck. Any help/suggestions greatly appreciated.