I bought a second endless summer hydrangea that is not doing well. The first plant thriving. The second one has bent stems (came like that) and the flower clusters are either not opening or the flowers that opened are white/brown. How to fix?

Their garden center will help you as they have many times....awesome place

On the young hydrangeas the flowers are too heavy for the stems and they flop, that is a common problem and is ok. If you cut the past blooms off they will perk right back up. IF the flowers are opening brown that means that the plant needs more water. Water at the base of the plant not the leaves or flowers on a daily basis in this heat spell. Hydrangeas are very hardy so they should be fine just keep watering. If you are still unsure you can bring in a picture of it so I can help you better.