In 116 degree Palm Springs heat after transplant 6 months ago my Madagascar Palm split vertically then keeled over.
The 6-footer had just begun to bloom when the heat hit. But other Madagascar Palms in the neighborhood seem unaffected. Too much water? It's on community twice-a-day schedule but with modified drip.
Certified GKH Gardening Expert
Hm... It looks like a severe case of pythium rot! This is usually caused by overwatering. Most tropical plants are well adapted to the heat, and anything you do to "help" them is usually "helping" too much.
From here, there might not be much chance for recovery. If the rest of the crown does not die off, then there may be a chance for it to shoot a new offshoot, but this is probably not going to happen.
These are considered "succulents" rather than a true palm, and should be treated as such.
This article will help you to care for these plants. The article pertains to indoor species, since most areas are not suited for this plant outside, but the care will remain the same: https://www.gardeningknowhow.com/houseplants/madagascar-palm/madagascar-palm-care.htm