The panel is made by Decorative Panels International (DPI)
The label says: 1/8" embossed tileboard
Model #627 - Design: "Toned White". (The face has shiny white
squares; the back is tempered hardboard)

The "application instructions" say the (un-installed) panel can be cut
with a fine-toothed handsaw. But how do I cut the panel that's
already stuck on the wall?