What kind of tv? For webos it’s potentially a bit complicated but also potentially stupid easy depending on which version of webos your tv has
https://www.webosbrew.org/rooting/
I would strongly suggest avoiding nvm even if it’s supported unless you’re very comfortable with hardware hacks. The others are all software and fairly easy to do if you’re capable with following instructions. The most recent, dejavuln, is fairly simple but can be a bit finicky (you may have to try a bunch of times) but lg is also rolling out patches for it so if your tv is updated you may be out of luck. It’s hard to say because the patches aren’t rolled out unilaterally. Webos is a bit confusing and there are many “branches” that all have similar features but wildly different numbering. If your tv is patched block updates by either disconnecting from the internet or blocking the above sites in your router and watch the webos homebrew discord (linked on that site). There are people actively researching new exploits and if one pops up it’ll be discussed in the discord first (and if it’s a big deal, like they expect it to be patched, they usually ping everyone to let them know to do it asap)
It’s a trivial repair assuming that’s the extent of the damage and there’s not any quirks associated with an extremely complex medical device that has no documentation whatsoever. Like maybe after not having the controller’s power supply connected for such a length of time there needs to be a calibration process upon bringing it back to life that can only be done with proprietary software
The biggest thing though is that by going in and fixing it yourself you open yourself to the possibility that the company will now say “oh this was worked on by someone else and that’s why it’s broken, we won’t work on it now”. That’s the state of repair rights in America, vendors are openly hostile to people who fix their own things even if they do it sufficiently. We used to have political representation that gave us regulations to allow us to work on and even modify our cars without impacting the warranty but that’s been eroded and there’s not really anything of that nature for tech stuff (other than judgements saying broken warranty seals don’t count for anything)