Why won't my phone turn on normally?

[AC Question]

I bought a Moto G (2nd generation and rooted) from a friend of mine and today I tried to install the update so my phone restarted and went into some weird mode (boot menu or something like that) so I restarted it and it loaded normally but then went right back into the strange state it was in before. I don't want to reset my phone as I haven't backed up any of my apps, pictures, etc. What is the reason for this and how can I fix it?