For those who are having blackscreen issue(andorid only) Try this method..
1.Delete the modded apk (make sure to save transfer code)
2.You have to wait at least a day for this method.
3.After 24 hours passsed, Go to playstore and download the official FGO JP apk here:
Fate's new RPG finally appears! You can enjoy authentic RPG even on a smartphone. A story that you can enjoy overwhelming volumes of over 5 million characters!
play.google.com
4.After installing the original apk.. download resources..and transfer your account..play at least one quest...
5.copy your transfer code again and uninstall original apk.
6.DOWNLOAD FGO MOD APK...MAKE SURE THAT THE MODDED APK YOU DOWNLOAD IS NO FPS UNLOCK...FPS UNLOCK IS THE REASON WHY IT IS BUGGY..
INSTALL NO FPS UNLOCK AND TRANSFER YOUR CODE...ENJOY PLAYING
this method is not 100% successful..but thats how i manage to remove my black screen issues..