After the online upgrade and restart of the mobile phone, it will automatically enter recovery mode. Without the double clear option, it will not be able to enter the system until the battery is exhausted. Urgent! ! ! As shown in the figure, the signature authentication of the installation package is wrong, resulting in unsuccessful installation, deletion of system files and inability to enter the system. This reason may generally be that the installation package is unofficial, which is very common in unofficial brush rom. Another possibility is that there is something wrong with the downloaded package. You can try to brush the official rom, of course, the line brush. You can also use adb side brush, but it is more troublesome. . . Or try the brick-saving function of some brushing software, otherwise it can only be repaired in the factory. In addition, remember to back up and double clear every time you upgrade your system, so that the success rate of upgrading your system will be much higher. The above is my personal opinion.