ShadowFactoryX
OMNIHILITY
Below the chrome footpedals, there's a microswitch soldered into the board. That's probably the cause they don't work; they've either worn out or you just stepped them too hard. If you know how to solder and basic knowledge about electronics, you could dissasemble it with patience and replace them. Those microswitches can be found at electronic stores. You just have to be extra careful when de-soldering and soldering, besides not to solder/cut any rails. Before the HD500 I had a Korg AX3000G; footswitches weren't good either, so there was even a pdf online explaining how to replace them. If you're not up to the task, just find and a good electronic repair shop and they should do it without a problem.
Unless there's something new below the sun, most boards are built that way, meaning the switches are not meant to be stepped hard. I know...that's crap because everything outside seems to have been built to last years, and many guitar players are into the Metal genre; makes anyone look like a pussy when switching presets on stage hahah. But that's the way to take care of this board. The HD500X seems to have better pedals, but unless they don't have an onboard microswitch, they are bound to be as delicate as any board.
I just got a nice new digital soldering station...but i still dont feel ok with doing that. Seems too risky of a job to do. But I did see this:
That looks like the perfect mod, but I do find it wierd that both of those switches went at the same time.