Is this a Mutant plant?

Suggestion, the plant sounds like it is actually bone dry. If the water runs straight through and into the tray, it may need a 'bath'. To do this you'll need a container larger than the pot the plant is in. Half-fill with water and 'submerge' the pot-plant into the container. If the pot feels 'light' when you submerge it, you may need to hold it down, then if it is very dry, the trapped air in the pot will come out and make the water bubble. If this is the case then you may need to leave the pot to soak for a little while. Then remove and remember to keep it moist and don't over water. Hydrangeas don't like the hot sun, and can burn and wilt easily. Semi-shade, cooler spot is better in my experience. Hope this helps.