Test voltages on the board at where the connector connects to it, if bad, check the wiring that goes back to the power supply.  If good and there's no obvious trace breaks or bad capacitors on the board, you're probably going to need a board schematic.

Awesome restore work, dude.

Excellent work.  Rare game, too.

Wow, that's some beautiful work you did.  Really precise stuff too.  Love that "New For '82!"

Congrats on the great find!

Can you do what they did with some cabarets and cut a hole in the rear door for the neckboard to stick out and then cover that with a with a plastic shield?

Excellent work!

This is a terrific project and you should be proud of the work you've done so far.  I'd love to do a cabaret for a multi-pac.

Someone made a bootleg?  You probably know the info on the original already:

https://en.wikipedia.org/wiki/Ninja_Baseball_Bat_Man

1993 beat em up, possibly 4-player like TMNT
the fourth arcade game by IREM to use a belt scroll perspective, following Blade Master, Hook and Undercover Cops.
"Of the 1042 units sold, only 43 units were sold in North America, making Ninja Baseball Bat Man quite rare (especially in the U.S.)."

Been awhile since I looked at mine but I just wanna say you're gonna be disappointed with the sound emulation for Gyruss in the 60-in-1 board compared to the original.  Most of the other games have decent sounds though.

1) The manual says to press TEST switch to go to the next menu page or SERVICE switch to go to the previous page.

2) Not sure about this.  You can wire up your cabinet speakers to your jamma connector for sound, right?  The speaker outputs are at pin 10.  The board allows you to adjust volume in the service menu.  If you're talking about a powering an outside amp you might need a separate line from your power supply to it or pins at position 6 on the connector are 12V.

Great story on the acquisition and congrats on achieving a childhood dream (and then some!)

I have one too.  Arcade monitors often have better resolution, but look at the connection to the TV your console uses.  I bet it's composite like mine which gets the job done but is a low quality video signal compared to what we use today (i think the best it can do is 360i?).  Awhile ago I saw people who would offer to mod the Neo Geo AES to give it an S-video connection which was slightly better and it wouldn't surprise me if they would be offering HDMI modding services now although I haven't looked.

Bank Panic and Puzzle de Bowling

Nice pickup!

Thanks for the report. Would love to see some pictures!