'failed to mount cache', 'failed to mount system', 'flash write failure' in yureka+
Seems like the eMMC chip got corrupted during the wiping process due to power loss - Always perform dangerous operation while phone battery is unless 50% or above. 

If the chip is not damaged, you still can flash your phone with a stock firmware. 

You can find flash files  (firmware) and the flashtool here. Download it and extract its contents.

This tutorial teaches you how to use the flashtool.