Download the LOLLIPOP factory image fastboot package for YU YUPHORIAhttps://cyngn.com/support/
Extract the contents of the flashing tools zip into the same folder
To make sure, check that system.img, boot.img etc files are in the same folder as flash-all.bat, fastboot.exe etc
Connect your phone in fastboot mode, steps for which are : -
a. Power off your phone
b. Press and hold the Volume Up key
c. With the Volume Up key, connect the phone to your PC/Laptop with USB cable
d. You can let go off the Volume Up key when Fastboot Mode is displayed on the screen
Run flash-all.bat by double clicking on it.
A command window will open and flashing procedure will start
DO NOT disconnect the device during flashing procedure
The command window will close after the flashing process is over.
Disconnect the USB cable, and boot the phone normally by long pressing the Power button.