Phone won't turn on.

[Szsz1111]

I have an lg g flex 2 for quite some time now and it started to get slow the camera stopped working sometimes and the battery started to lose its capacity but today it turned off and i couldn't turn it completely on. The phone makes it to the lg logo and sometimes to the boot animation but then it turns off. The battery could be dead but im not sure though a few weeks ago I noticed that if used it while it was charging it was still going down in percentage. Also if i let the phone rest the more i leave it alone the farther it gets in the bootup process if that makes any sense. I would appreciate any help.

 

[Angablade]

Take the main board out, and bake it on an aluminum stand in the over for 10 minutes at 310F.