If you have a signature certificate! Install the signature file on the mobile phone and enter the signature software. The first item is the file that needs to be signed, the second item is to put the file with the suffix key into your signing certificate, and the third item is to put it into the cer certificate file. Finally, just choose the option of sing to sign, and then go to the file root directory of the software you signed later. If an X is added to the software suffix, it is signed software. Just install it directly.