Failed upgrade, now stuck in recovery mode(Myphone model:my27)
First, turn off the phone by using the Power button.
Press and hold Volume Up + Volume Down + Power key for some time.
When you see a menu with two options, remove your hand from buttons.
Afterwards, press the Volume Up to enter Android System Recovery.



 5. Select the "Wipe data / Factory reset" by using the Volume buttons and press the Menu Capacitive key for confirmation.


Then choose "Yes--delete all user data". Use Volume Down to scroll and Menu button to select.
Success your reset.
Here I provided more mobile hard reset solution.
Thanks......!!!!