Just got it repaired, now there's a new problem

I recently gave my laptop to best buy for repair because of cpu throttling, they fixed that problem but now there's a new problem. The laptop randomly shuts down during gaming. It manages to shut down every time I do timespy benchmark. I did some more testing, and I found out when I unplug the battery during the timespy benchmark, it doesn't shut down. So now that I know it's a battery problem, is it possible that I can fix it on my own? Or should I go get it fixed again? I really need to use my laptop for work and I really don't want to give them my laptop for a month again. Pls I need help