Default [Q] How to fix second sim on lewaOS of Viettel v8403

Please help me.
I'm using lewa os for Viettel v8403(zte v790). anything alright, but i have two problem with it.
+ First, please tell me or help me to fix signal second sim, first sim is working, but second sim not working. Sometime it's have signal.
+ Flickering and i fixed it by SetCPU, but it's the way temporary.
and this link of rom
p/s my english is poor, sr