Xiaomi Mi10T Pro Grey/Black Screen after 0% won't turn on, need help!

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Hello, i have a Problem with my Mi10T Pro.When my Battery % reaches 0, my Phone won't turn on even after charging.Reboot does not work. It goes from Mi Logo -> Loading -> Grey/Black Screen -> Mi Logo.Factory reset is no Option since i have important Files, Pictures and Gaming Accounts on this Phone. Does anyone know what to do? Or should i just go to the repair man?