I have a brand new Nexus 5X locked to a Japanese carrier called y!mobile (run on the Softbank network). They won't unlock the phone unless I open up a contract and stay with them for 6 mos. This is not an option.
I tried two online unlocking services (simdoctor and sim-unlock) and neither of their NCK codes did the trick (they were identical, btw).
Prospects are not looking good. I saw a reddit thread where someone suggested reflashing with a stock Nexus ROM. I'm curious if this will be a waste of time, as I've read that the carrier lock resides nestled away on hardware somewhere unaffected by OS. On the other hand, this phone, as far as I know, has no carrier-specific alterations whatsoever (other than the lock)--so I guess I'm holding out some hope the Nexus devices might be an exception.
Will re-flashing do anything for me? Any alternatives you can think of? Why are the brand-specific unlock codes choking on the 5X?