You don't need to flash a SBF again wiping from stock recovery should fix it.On my SOC DEFY SB 3.1 ROM tether is not working.
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After few days on CNA 3.6.6 - UNBELIEVABLE SMOOTH!!!!!! - I am going back to WIUI.
The problem with cant mount still present.
Here are the steps CNA 3.6.6 as ROM:
1. Wipe data + dalvik.
2. Restore nand backup.
3. Reboot.
4. Stuck on M logo.
5. CWM informing E:\cant mount "thing".
6. Installing SB 3.1.
7. Reboot.
8. CWM - Tools - Formating to EXT3.
9. Reboot.
10. Wipe data etc.
11. Restore nand backup problem restoring nand secure because cant mount.
12. Loading SBF.
I will add that in the OP WiFi & USB tethering not working.... use an app instead.
Let's Go ^_^