The Huawei MediaPad X1 (models 7D-501u/L and 7D-503L) officially runs on Android 4.2.2 or 4.4.2
Method A (System Menu): If the tablet is running, go to Settings > System Update > Menu > Local Update. Select the file on the SD card to begin. huawei mediapad x1 70 update lollipop install
Requirements: Requires an unlocked bootloader and a custom recovery like TWRP or CWM. The Huawei MediaPad X1 (models 7D-501u/L and 7D-503L)
If Method 2 fails, you can use the Firmware Finder for Huawei app to locate official OTA packages. Huawei MediaPad X1 4.4.2 KitKat update (HOWTO) Unlocked bootloader Custom recovery (TWRP 2