First of all, you should distinguish between certificate error or certificate expiration 1, certificate error.

There may be an error in the certificate file. Please check whether it is your own certificate file first. If not, please reapply.

There is also the unsuccessful signature. The unsigned software is. Sis, and the signed software is. sisx。

You have to copy the signed copy to your mobile phone.

Just pretend. 2. The certificate has expired.

Adjust the phone time as mentioned above.

I hope I can help you. Student 2