gcotterl wrote:
Hi Jon,

The panel is NOT a cement backer board. Its face has shiny white
squares and the back is tempered hardboard.

Oh okay, I gotcha, that laminated stuff. I'd use a straightedge and several
new razor blades in a good razor blade knife. Hold the straightedge
securely and keep cutting passes (away from your fingers) until you make it
through. Flip the blades and replace them frequently - they are a
consumable item. It's gonna take a lot of passes, so be patient.

Jon