SamyGO

Why do you stuck on installing firmware? Just root it, don't flash it....

So what? You can't have all functions at that tv. You are limited already absence of Lan port...Anyway...

Might be you can just try ExLink access from VGA/Service port.
SamyGO definitely does not support your firmware (yet). That doesn't mean SamyGO is not for you/your TV...
SamyGO is information share community. If you find a way to improve/hack your TV, than you can tell here how did yo make it and other users learn about it.
You can hack your TV with information on this site. They will be help you about learning TVs internal structure...
On your situation, there is no user came and tell about how C350 tvs could be hacked.
Keep trying, if you find anything, you are free to share with us.
Than SamyGO will support your TV model because of your work.
That is how things works here.
Regards.