This question already has an answer here:
I'd like to upgrade my old Verizon branded Samsung Galaxy Note 2 (SCH-I605) running 4.4.2 to Android Marshmallow to get the latest updates (specifically the security updates for StageFright), but thus far I haven't been able to find any documentation on the internet showing how. My Nexus 6 actually gets it's updates directly from Google thus guaranteeing I always have the latest patches.
I'm tech savvy, but I've never tried unlocking/rooting/modding a phone before. Can anyone provide any guidance on what tools to use and what ROM to install?
Note: I understand rooting/modding a phone comes with risks and accept full responsibility if I 'brick' my phone.