>>893305Hmm.. Can't even find a parts-only hulk you could rip a panel off of, nothing out there.
Between the buttons and display the buttons will be the easier of the two to reverse engineer, but without a schematic I wouldn't be game to try. It likely has a proprietary (reads; no datasheet) chip sitting on the chassis end of the ribbon and with no reference to its pinouts, or what sort of chips were in the panel to create signals, you are in the dark about how to feed meaningful data back into the chassis. The screen looks like it would be a custom VFD (again, very lucky to find a datasheet) and while it may be driven by a common interface chip like a HD44780 or similar, not knowing the custom addresses for the custom screen elements will roadblock you here as well. This assuming you can even get that type of VFD as a spare part of course.
In my travels I saw a OM/SM for $100USD, considering the price of the unit it may be worth it and you could flip the manual once you're done, though consider this. It's an expensive unit. Why was its face ripped off in the first place? If a second unit got smashed up why not swap the whole units instead of opting for surgery? Does this chassis have deeper more painful faults that made it a candidate for spares? Don't mean to scare you off, but in my experience it is generally the most expensive kit I come across that is the most broken because if it were economical to fix, it would be getting fixed.