If the physical buttons or SD card method fail, try official software recovery tools. Install Huawei HiSuite on your PC.
Press and hold simultaneously.
Encountering the message on your Huawei MediaPad 7 Youth (S7-721u) typically signals a signature mismatch. This occurs when the device's bootloader—which is likely locked —detects a recovery image that has been modified, incorrectly repacked, or is not digitally signed by Huawei. Understanding the Error huawei s7721u recovery image verify failed repack
Use a reliable MicroSD card formatted to FAT32 . If the physical buttons or SD card method