If you boot your MTK Android (e.g Tecno, Gionee, Infinix, Opsson, Innjoo etc) phone and see:
" Encryption Unsuccessful
Encryption was interrupted and can't complete. As a result, the data on your phone is no longer accessible.
To resume using your phone, you must perform a factory reset. When you set up your phone after the reset, you'll have an opportunity to restore any data that was backed up to your Google account "
Then your /data or /SD card partitions might be corrupted . To resolve this issue, click the "Reset phone" button at the bottom of the message or boot into recovery mode (see http://forum.hovatek.com/thread-479.html ) and select the Wipe data / Factory reset option. You could also wipe cache partition for good measure. If the issue persists then format the SD memory card, slot it back in then reboot the phone .
* Note: If you encounter the mount /data error then read http://forum.hovatek.com/thread-580.html
If a factory reset in recovery mode fails to fix it, boot into factory mode (volume down + power button). It'll display in Chinese. Select the option which has "eMMC" in its name and wait for it to complete then reboot the phone.