Screen dims and unresponsive, horizontal and vertical lines

Yesterday when I was driving my car using google map on my iPhone 5s suddenly some horizontal lines are displayed on the screen and the screen became unresponsive.

Initially I thought it is just a software glitch and I did a hard restart (home button + power button). The phone worked for a few seconds and suddenly those lines appeared again and the screen went dimmer and dimmer and the screen became unresponsive again.

Later I realised that if I press the power button to turn off the screen and then press home button to turn the screen back on, the screen is restored to normal and the phone would work for around 30 seconds before the same problem happens again.

Later last night, the problem was gone and I could use the phone without any problem.

Then this after, the problem happened again.

I'm pretty confident that this is a hardware problem because I am still using iOS 9 and I haven't upgraded my iOS for a few months.

It seems to me that the problem lies in the screen but the screen works fine for the first few seconds when I press the power button and turn it back on. Maybe it's to do with the power cable inside? Hopefully not the main board.

Any suggestions? Has anyone had this problem before?