It's an early Konami Advantage, and what Badbaud meant by "They don't exist, the batteries went dead several years ago", he was referring to the EL Keys for those older machines. The EL Keys all had batteries in them, which would allow access to the menus and perform Keychip features such as RAM Clear and set up.
The newer Advantage machines use CF Cards instead of the ELs. They're much easier to work on.
Without being able to access the Attendant Menu, you won't be able to clear the Hand Pay, if that's what it actually is. I've never received a Hand Pay Jackpot, so I'm not exactly sure how to clear one on the Advantage machines.
It may be possible to swap your Software Chips over to a newer K2V MPU that uses the CF, but I'm not 100% sure that the 2 are interchangeable. Hopefully an expert will chime in and let you know more about what options are available to get your machine playing again.
Curtis ash100