Yu is the brand-name given to a new line of products by Micromax aimed to counter the competition from likes of Xiaomi (Mi Vs Yu!!), the first smartphone of the series Yu Yureka offered a great combination of hardware and software (CyanogenMod) at an very affordable price. The handset recently got an update to Google Android 5 Lolipop (CyanogenMod 12), everything worked ok but it seems it introduced a bug which would result in blank screen when waked-up from lock-screen or after a reboot and also during calls. Here is how you can fix both issues - the black screen during the call and the blank screen after reboot or wake-up.