@yuki_the_maven This may not be correct, but I think:
Iirc Cyanogenmod is one of if not the most popular third party firmware replacements out there. And I think in order to install firmware, you have to root first. So you might look up your phone model on their website, see if someone's done a handy guide, and use whatever rooting method they recommend there. Still might be/feel sketchy though, ymmv.