Question [Q] [NEED HELP] vs980 stuck

Dear all,

I have bought my lg vs980 1 month ago and it was working fine until yesterday, I was transferring music from pc and after a while found out that my phone screen went black and unresponsive, however I still can see the task bar in the top and a buttons line in the bottom. Tried to restart by pressing and holding power button for 8sec. but again it boots normally and after ~ 15sec goes black or freeze (if I managed to open smthing ) and unresponsive. Also tried to do the same things without sim card, same problem. Please help??
Phone is completely stock, unrooted.
Using it in Global mode.