problem in factory reset after updating yureka to cm12

Hello friend I updated my yureka to cm 12 two months ago I facing a problem in my phone when I going to do a factory reset it done successfully but after when my Yureka phone is starting it shows android is upgrading in first boot. every time when I do a factory reset in first boot it shows android is upgrading. Help me guys to get out from this problem.
I am very thankdul to you.