Macbook pro shutting down even in very light usage.

My macbook pro 13" early 2015 shuts down randomly. It shuts down even when watching youtube or any other very light tasks, then the next moment when I power it on, it won't even reach upto the login screen. When I keep it idle just the screen turned on and doing nothing else it works for a very long time. I guess it is somehow related to CPU/GPU temp. Also when the CPU is is cold and I start it, the screen distorts and it takes nearly 5 mins to recover. Even after the screen recovers it is covered with equally spaced light grey very thin horizontal lines. I have already replaced the thermal compound and its was of no use. Is there anything else that I can do?