Another weird 3DS battery drain question

I have a regular 3DS that appears to have an issue with the battery; when the console is closed/asleep, it seems as though the battery is discharging like normal (for example, the display showed 50% battery after two days closed and unplugged). However, when I play a game, the light will suddenly flash red, and the console will power off soon afterwards. This cam also happen if I just open it; I’ll turn the power back on, and even though the display shows two bars on the battery display, the light flashes and the system shuts down. It’s currently in sleep mode again, amd the light is glowing blue. I’m planning on trying to discharge the battery “naturally” like this to see if cycling it helps, but beyond this, is there anything else I should look for? Thanks.