Mobile phone security authentication settings do not allow downloading and installing unauthenticated software or software from unknown sources.
The software download and installation failed due to the instability of the mobile phone system caused by cleaning the package.
The sd card is set to read-only attribute for various reasons, so it is impossible to download or install software in the sd card at this time. Among these reasons, the unexplained software installation failure caused by sd card being set as read-only should be the most common and the most difficult to solve. Many times, after the sd card is set to read-only for unknown reasons, it is useless to format the sd card with the formatting function of the mobile phone, and it is impossible to format the sd card on the computer.