Why does my computer restart after picking it up

When I pick up my laptop from the left side near the shift and caps lock key the screen displays lines and then the keyboard and trackpad become unresponsive and then it restarts. I replaced my HDD with an SSD last year from iFixit.

I went to the Apple Store and the technician told me that an SSD is NOT compatible with my model of MB Pro and should not be used it although iFixit's website clearly says it.

Can anyone help me out with troubleshooting this issue. I contacted iFixit's support and got nowhere, they just told me that they have the same SSD in the same model MB Pro as me and it works just fine. They also told me to reset the NVRAM and SMC which I've already done.