You did your due diligence and found that it's a dead end.
Present that information to the client and offer solution to get them into 2016 technology from a company and products that you can support.
You're not going to get the few hours you already spent back and continuing to dig deeper will only burn more unbillable hours that are not going to get you any ROI.

Trust me, I've done that several times over the years, only to hear the customers say "Oh well, Thanks".

If you'd like, I have $15,000 Russound Sphere system I can sell you.
The company is still very much in business, but chose to scrap the product and ran out of parts to support it. I've moved on to their newer product lines.
Every dealer on here has shelves of old VCRs, media players, amps, keypads, and TVs that were once pride and joy of industry, but have since been obsoleted.

Stop feeling sorry for a client that invested with someone else in product that's now dead.
Offer current solution you can be proud to support.