Stock firmware for many H3 devices is often stuck on Android 4.4 or 7.0. Moving to a community-supported firmware offers:
A full H3 firmware image is not a single file but a collection of partitions: Allwinner H3 Firmware
are popular for TV boxes, offering a smoother, TV-optimized interface compared to stock tablet-style Android. Stock firmware for many H3 devices is often
If your device won't boot, try the "toothpick method" —pressing the reset button inside the AV port while plugging in the USB cable to force it into a flashable state. offering a smoother