Iphone 6 bad nand

Hi guys, a few days ago my iphone 6 has started to go off by himself, and sometimes it worked and sometimes not, the application crashes and sometimes to restart did not see me do it phone settings, I made at least 5 rehabilitated (in recovery and DFU ) then today did not go beyond the apple logo, thus assuming that the problem was the NAND I made a reflow when I restored it gave me error 9 and then you are no longer turned back on, I wanted to know what you think? If the problem was actually the NAND, I can replace it with one of a telephone with iCloud Locked?
Thanks in advance