Hello! I am Grandt from Gumi Support Team at your service!
I am happy to help you in your endeavor, summoner!
*cough* *cough*
You haven't paid us enough money. Come back once you have paid us enough.
jk
Aaaaanyway, Let's go list some stuff that you can do to solve your problem.
1. Try uninstalling Brave Frontier and reinstalling Brave Frontier if you haven't.
2. Try deleting the tweak, reinstalling the .deb file and respring your phone. See if that works.
3. If nothing works, then you can try to open Brave Frontier. If it crashes, go to multitasking and access Brave Frontier from there. It usually takes a while before you can access the game. If you have tried for a while, then it doesn't work.
4. Check your date and time, make sure all previous Brave-related tweaks are uninstalled.
5. Do you have any tweaks that interfere with applications? Make sure that those kinds of tweaks don't interfere with Brave Frontier. If you only started having this problem, try deleting the latest tweak you installed on your phone.
Message me again if you have done the above steps and it still doesn't work.
Thank you!
~ Mercenary Grandt
Elysian Mercenary