I am a little late on this, but I don't think you need to reset it at all. I had a horrible accident where I smashed my iPhone to pieces...accident for my phone not me. I bought a new phone right away.
I did not reset my Band at all.
I went into pairing on the band and put it into pairing mode.
I logged into the MS Health App and thought I went to replace my Band. It went through the process and everything has been great.
Dave