About displaying NavigationBar on the S700 platform: go to the framework/base/core/res/res/values/config.xml file to modify the property value of config_showNavigationBar to true, and then under the description of PRODUCT_PROPETY_OVERRIDES in the device/actions/s700_cb6/device.mk file Add qemu.hw.mainkeys=0 (0 is displayed, 1/null is not displayed)
The above S700 platform uses the Android 5.1.1 system code, which is valid for personal testing.