Keep holding both buttons until the screen turns on. You will see the ITEL logo, then a dark screen with small text.
Use the Volume Down button to navigate to the option labeled "Bootloader" or "Fastboot" (if available). How to Open Bootloader Mode on ITEL A48
Type the following command and press Enter: Keep holding both buttons until the screen turns on
Release both buttons. You are now in Factory Mode or SPD Upgrade Mode – this is the bootloader-equivalent interface for Spreadtrum (Unisoc) chipsets used in the A48. How to Open Bootloader Mode on ITEL A48