Hello, I'm TV Tech1 and I'll be working with you to identify and help you resolve your problem.
Hmm, both the USB and Video outputs on your recorder are in black and white.
The TV can't be upgraded, unless Panasonic has created a Firmware or Software update that specifically rewrites the programming to accept 4GB cards. That would be explained on the software update itself.
If you have an SD card that's 2Gb or less, I would run a short test and see if it shows up on the TV when inserted into the TV's card reader.
What happens if you connect your SD card to your computer and view it on that? Is it still black and white there? That would at least tell us the Camcorder isn't delivering color signal to be stored.
And if so....then I would look at the actual video settings on the camcorder.