Windows server 2012 reboot arbitrarily

Our customer occured the server ‘Amber LED’ warning light, our customer experienced discomfort a lot.

So, they tried to through the replacement of the cache battery. And it was solved.

But, additionally it comes that ‘Operating System Failure (Critical Error) and the server reboots 2-3times arbitrarily.

We want to know what is the problem and method to solve

Thanks.