Phone gets hot

[Tye]

Hello everyone, I'm new to the forum and have come in search of help. 

I have had the M2 since May of last year, so just over half a year. Recently though, the battery on my phone has began to heat up to an uncomfotable degree where I find it difficult to even keep hold of the phone. I've looked into what kind of apps I have open, but I don't feel this is a problem. It's not just your usual overheated phone either, its borderline unbearable. This also causes my phones battery life to drastically drop and when I go to charge it, I am propted with the message that basically says more power is being used than what is being charged. Or something like that, I'm sure some of you will know what I'm talking about.

Now what with it being the M2, I know I can't just simply take the phone apart and replace the battery with a brand new one. So what should I do? Do I have a warranty I could take advantage of? When I got the phone back in May, it was on a 24 month contract and due to being relatively reliable with phones, I turned down any insurance. 

Any help with be very appreciated. Sorry this is quite a long post. I look forward to hearing from some of you.

[Hampus]

Hi and welcome to the community! Since you're new please be sure that you have checked out our Discussion guidelines.

If the phone gets to hot, it will automatically power of to prevent overheating. Have you tried to boot the phone into safe mode to see if you experience the same behaviour?
/t5/FAQ/How-to-boot-your-phone-into-safe-mode/m-p/348008

Otherwise, a software repair via PC Companion would be recommended:
http://support.sonymobile.com/global-en/tools/pc-companion/

In PC Companion you press start on Support Zone > Start on Update the phone/tablet software > Repair phone/tablet (the blue clickable link in the message) > Follow these steps without having your device connected to the PC.

Follow the instruction that appears in the program and do not connect your device until this guide tells you how to connect it.