This game had been in my collection for about 14 years. I decided to make a play but the game displayed a RAM NG text and didn’t boot

 

After checking the schematics I decided to prove rams and some devices but the signals were healthy

Thanks to Kale from mame team, I discovered that the game does a simple check but decrementing some values in ram and read them back.

Therefore I decided to desolder the program srams to check if they were good. The game has only 2x 2016 toshiba rams.

This brand is known to be not really reliable in comparison to others

After checking the first one I got confirmation that it was bad

I resoldered it and this time the game booted with RAM NG briefly shown and behaved strangely. You couldn’t shoot and parts of the scrolling was repeating.

I decided to desolder also the second one since the game still complained about the ram.

Also the second one was bad!

After changing also this one, the game was 100% fixed