My W2C shows blanks in Boxes 1,2 and several others where the original W2 showed a dollar amount. Do I leave these blank when I file, or fill in the original W2 totals?

I was laid off from my employer in late 2016 and received a large severance package. I returned to this employer in early 2017, and had to pay back most of this package (over $15,000). It appears this was the correction in Boxes 3-6 on my W2C, but all other boxes, including 1 and 2, were filled in on the original W2 but not the W2C. I would like some guidance on how to report this.