Phone auto shutdown topic

My phone suddenly shutdown while browsing. I was on CM12 build 19feb w Franco kernel. Restarting it only lead to auto shutdown after bootup. I install another rom Temasik n similar - phone bootup successfully n than shutdown. Than I tried restoring from 2 rom backup n also later flash back original firmware - in all scenarios phone bootup successfully but goes into auto shutdown mode. Appreciate any help on this. Phone now cannot be used