hello guys

first of all let me say sorry for my bad english, but its not my main language.
i bought a OPO about 6 months ago and i was really happy with the phone until i started to used it alot. during the day i use it at work for browsing and music and after work i play some games on it.
thing is at the begining i felt that the phone got a bit hot after some use but it seemed not to be too much but around 2 weeks ago i started to have some problems. even with only wi-fi and chrome running my phone is getting temperatures between 37º and 40º. at this point i can feel that the top half of the phone is getting really hot, back and front, but most at the back.
if i start a game, like plants vs zombies, phone gets even more hot and at this point a yellow spot starts growing at the top right corner of my screen.
before i contact the support i installed a diferent rom just to test and now i would like to have some feedback of you guys before i try to contact support, wich seems to be really bad :S
any ideas? any thing i can do to fix this?

tnks for all you time.

When I turn on the phone, I saw this on up right corner and made me sad...

What is it actually?

I have a LG G2 6 months old, day before yesterday I noticed a yellow stain on the screen.
I sent the phone in service, care put recognize a guarantee? Do you changed the whole phone or just a touch / display?

PS: I have a guarantee