Lg G4 unroot question vzw

I recently bought a used lg g4 with only 2 weeks use, when i got the phone it was already rooted. How can i find out what was changed on the phone im fine with it staying rooted it just seems to loose battery charge too fast and gets hot when installing apps, is this common on g4 or has the previous owner messed with cpu speed? If its only rooted would anything happen if i tried to update the phone with a new update comes out?

Did the seller advertise the phone being rooted? If not I would ask to return it. If you payed with paypal you would easily get a return if the seller won't give you one. I'm not a fan of buying used smartphone especially from individuals.

the thing looks brand new and i got a great deal on it

I have seen water damaged phones look brand new.

Usually if you are rooted you will not be able to install OTAs.

The phone will get warm but only when gaming or if you have the screen on a while.

You can always look for a stock ROM on XDA to see if it makes a difference in battery life and heat.

I already looked and its very locked down. I didn't even find any stock roms.

when i game u used cpu-z to check temps and it said 60-65C is that okay or too hot for an android phone? i know its okay for pc's but i dont know much about safe temps for phones

Thats very hot for a phone. The CPU itself can go up to 80C-90C, it just the other components of the phone that can only take up to 60C before failure. I would take a look at this.

The temp I have you was the cpu die temp not back cover temp

I am aware of that. If I were you I would return the device. I buy/sell/repair phones and this sounds like a bad phone.