It is hard to say why the new stems died off, perhaps they were bitten by a cold snap while they were still tender. However, it is likely you don’t have blooms because you cut the old wood back to the base—those were the branches that would have produced blooms. You want to keep year-old wood for a few seasons before removing it. The new growth, as it ages, will take its place. That is how you keep hydrangeas blooming—they should always have a mix of older branches and first-year growth.
It is hard to say why the new stems died off, perhaps they were bitten by a cold snap while they were still tender. However, it is likely you don’t have blooms because you cut the old wood back to the base—those were the branches that would have produced blooms. You want to keep year-old wood for a few seasons before removing it. The new growth, as it ages, will take its place. That is how you keep hydrangeas blooming—they should always have a mix of older branches and first-year growth.