The device will reboot automatically. First boot can take up to 10 minutes (Android optimizing apps).
Official firmware is rarely hosted on a central site; instead, it is typically distributed by specific device manufacturers or community repositories: Allwinner Quad-core T3 P1 Firmware Download -PORTABLE
Look for a product name or board name in your device’s Settings > About Tablet/Device. Alternatively, open the unit – you will see silkscreen printing like: The device will reboot automatically