Have you been able to perform a systems diagnostics to check for hardware issues yet?  If not, please run Dell SupportAssist, make a note of any error messages encountered and post back.  If there are none, please run the ePSA testing by pressing F12 at startup and run the diagnostics.  If there are no error messages, then it could indicate either a software or driver issue.
Screen auto turn off time to time, not the heating issue but something starnge
Inspiron G15 5510, screen auto turn off