I guess you have not read what I have written. I have tried to flash original fw and it didn't resolve issue with SIM error. That is exactly reason why I have tried other fw including chinese ones. ONLY chinese one appear to have fixed it first. Initially my phone worked for few days. Now also it is working without cellular functions, much better than SIM error and phone being unusable. There are many people like me who faced exactly same issue. For some they had flashed other regions fw but for some this error has appeared without any reason. Like after updating sw via sw update on phone or one fine day they restarted phone and this error showed up. Hence do not think that you know everything and other's are blind followers. People will try to find resolution by trying what has worked for others after they have exhausted all other logical options.