I've just bought a new Blackview A10, my first smartphone, which has Android 7.0. Connecting it via the supplied USB cable to my Windows 10 laptop, it charges the phone and in Windows File Manager there's an icon for it but with nothing inside. My previous phone, a basic Alcatel, automatically asks if I want to charge or to use the phone's SD card for storage. The A10 is not showing this. There's nothing about USB in Android Settings on the phone. I looked online and put the phone in Developer mode, which shows that it's got Media Transfer Protocol turned on. I installed the Android ADB interface which is now showing in Device Manager with a warning ! sign. But still Windows doesn't show anything more, such as the internal storage and the 16GB SD card. I've tried different USB cables which work with other devices.

Any ideas, please?