The Xiaomi Redmi Note 9 is a mid-range smartphone by Xiaomi released April 2020. It has a 6.53" IPS LCD display, a 48 MP main camera, a rear-mounted fingerprint sensor, a 5020 mAh battery, and runs on a MediaTek Helio G85.
I'm assuming you mean it powers itself off? I'm by no means an expert but that sounds like a power delivery problem. My Nexus 6P did some funny stuff like that. There are some apps out there that will show the remaining battery life. I would start there.
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