Chosen Solution

I found this piece of history on my wife old house attic, I’ve replaced the rear battery, but on start give me this “Illegal Instruction” error. There’s a way to fix it? Thank you all Alex

Traditional The traditional Macintosh error codes are displayed like this: 0F0003 Where F indicates an exception occurred, and 3 indicates an illegal instruction occurred. Here are the error codes: https://udcf.gla.ac.uk/~gwm1h/Error_Code