SamyGO

Wrong. You can brick your TV with modified USB scripts too.
Untouched Modified Firmware Flash and Untouched USB scripts will not break your TV.
But your modification also could brick your TV. Don't scare from make your TV bricked. You can revive it later with ExLink cable..
Please read this wiki article.

I want to say that, I think it's really hard to make TV (non-CI+ ones) dead. If it's bricked, you can revive it later.
Which makes TV bricked? Simply if you play with "bml.erase" or "bml.restore" tools of tv. Or wanted to write on /dev/bml0/6 or 7... And if you write faulty firmware that modified by manually (SamyGO Firmware Patcher is intended to error free ) than this make your TV brick too. But you can recover it via ExLink cable and with little work