Flashing a firmware for SC-02H model on SM-G3950 model of Samsung Galaxy 7 Edge

Problem: I have a phone I bought from HK and using in Japan. It has been working perfectly fine for 2 years until recently when I changed the service provider. Unfortunately, the service provider has washed its hands off the problem claiming the country of origin. Possible Solution: I read in many forums that it could be an issue with the CSC. So I am presuming that if I can start updating the phone with Japanese OTA it might work so I intend to flash my phone with the Japanese firmware though I can't find a reference where the different firmware are claimed to be compatible. My concern are the following: 1. Where can I determine if the firmwares are compatible and if the worst comes to pass can I reset my phone to default factory settings? 2. If I download a HK firmware and reset CSC to SMB (I think it is for Japan), will i actually receive OTA updates for Japan even though the firmware itself is for another location?