Win Blu Hd Lte Display Problem Troubleshooting

[Windows Central Question]

Recently i came across display problem. When i am using whatsapp in wifi network my phone's display starts blinking and gradually goes dark. Now the display glows grey in colour. Phones battery level is 40% by the time. Very rarely, sometimes the original screen comes for few seconds and starts flickering and goes to grey colour screen. I tried to restart by pressing volume down and power button. But still not working.
I tried hard reset as per the instruction which you have given by Blu.
1. I pressed volume down and power button at the same time.
2. Display glows in grey colour and after 4 seconds mobile vibrates.
3. I left the power button and get hold of volume down button.
4. (No exclamation mark came. But phone starts vibrating again).
5. Then i pressed volume up, volume down, then power button and then volume down.
6. Once i pressed this phone vibrates and grey screen goes off and seems phone restarting.
7. But again grey screen comes.
8. Display glows in grey does not go off even after i press the power button.
9. After about 2 minutes phone vibrates automatically.
10. Now i press the power button. Display goes off.
11. During all this process display glows in grey colour only.
Kindly help me to solve the grey colour display problem