Hello. I have a problem with the gsm signal: the phone finds it difficult sometimes to lock a network. I previously had 4.4.25 version of the Chinese rom and updated through system update to 4.5.9 multilanguage. I didn't wipe or anything. I need to get the phone fully wipe so I can install the rom from scratch. I tried using from cwm format system, but it won't do anything. Also, I can't clear the cache from cwm, the phone just shows "formatting cache" for ever. Does MiFlash fully wipe the 2 systems? Is it safe to use it in my situation?