Some Algiz RT7 is not detected by the PC when connected via the micro USB port meaning it won’t charge and file transfer or ADB will not work. It’s because some Algiz RT7s are shipped with USB Host mode enabled by default.
This means that the device will act as a USB host and not as a client. To change this, open Settings and go to USB Host. Disable the host mode and reconnect any USB cables currently plugged in.