Not an answer but a follow-up question: is there open firmware for TVs like Openwrt for routers? I have never heard of such a project, but it sounds like it would be useful.
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Any tips and pointers would be much appreciated, in terms of common ways to search for and exploit vulnerabilities, or the exploitation of other televisions. Alternatively, if this is an absolute fool's errand, and the whole thing is locked down tighter than Fort Knox, a firm warning that this is not a good thing to dick around with over a weekend would also be appreciated.
The software on tvs is awful. Plus many new tvs have ads baked in.
An open source OS would be a dream.