Macbook Pro 15" Retina (Mid 2015) Random Rebooting

Recently bought a refurbished Macbook Pro 15 Inch Retina Model and at first everything was great. I installed everything I needed, transferred all my files etc. Anyway about 4 days later I see my battery is getting quite low so I plug it in for some juice and just close the lid. I come back to a green magsafe indicator and I open the lid and theres just a black screen. Long story short I couldn't get it to turn back on so I made an appointment with Genius bar and they sent it our for repair. I go and pick it up today and the repair says that the logic board and I/O Board were replaced. Yay my computer tuns on but now I get random reboots. At first it would just shutdown and not restart. But now it just reboots and the funny thing is, is that its not a kernel panic and there are no serious errors in the logs and when it comes back on its like a normal restart like nothing ever happened. I did a SMC reset and a PRAM reset to see if that would help but not quite.

Please help I run a business and cannot afford to be without a computer again. Specs below.

MacBook Pro (Retina, 15-inch, Mid 2015)

Processor 2.2 GHz Intel Core i7

Memory 16 GB 1600 MHz DDR3

Graphics Intel Iris Pro 1536 MB