Phone says "Cellular update error", and the modem firmware is missing.
I have an iPhone 7 that is about a year old, and a couple days ago it started saying "No service". At first I tried the obvious steps of restarting it and taking the SIM card out / putting it back in. Then it appeared fixed, but it was not working anymore the next morning. So while I was at work, I tried everything in every help article I could find. I tried looking for a carrier update, resetting the network, using a friend's SIM card, and I even tried updating the phone to iOS 12. When I tried directly on my phone to update it, it said that I had no internet connection and could therefore not verify the update (I was connected to wifi, so I'm not sure why it said this). So, I went to update it in iTunes. It took a while, and my phone eventually showed a screen that said there was an error. iTunes said I had to reset the whole phone to update it. I obviously didn't want to do this, but it appeared I had no other choice. So I said yes. It appears that nothing was reset since all of my apps/folders/etc. are in the same place but with the update. Finally, after I updated the phone, a new error message appeared in the status bar - instead of just "no service", there is also an exclamation point in a triangle. Also, if I go into the settings, it says "error" next to "Cellular". The error has a "Learn more" link that shows me this: If you see a Cellular Update Failed or Apple Pay Not Available alert after iOS update or restart - Apple Support
I live in China, so I made sure to diligently look on Apple's website and find an authorized Apple repair shop. They told me that they found that the modem firmware is missing from my phone, and they said they can't even send it to be fixed unless I have my original receipts since I bought it in America. Also, even if they could fix it, it could take a month since they'd have to send it to a factory in America. Apparently there are some weird laws about what hardware an authorized Apple service provider can have. They said a big Apple store could likely fix it. They also confirmed (like the article) that fully resetting it could mean I wouldn't be able to activate it again.
Also, as another bit of the issue, my phone dies super quickly now even when I have it on airplane mode and just connected to wifi. And also, it gets hot super easily.
There is a big Apple store opening near me on Friday, and even though the first appointments aren't available until Sunday, I think they will try to help me since this is obviously a desperate situation.
In summary, what do you think, specifically, is wrong? And do you think they can fix it at an Apple Store in China? Also, if I don't have Apple Care, will it cost me an arm and a leg? I bought this phone about a year ago, and I'm quite sure I did nothing to cause it. So I don't think it's my fault.
iPhone 7, iOS 12, null
