You are diving down a rabbit hole; You can spend $60 on a CPS addendum, but if it isn't the correct part you will never fix your problem.
You can't buy a second hand RCM and expect anything other than trouble.
Did you comprehend post 9 and 10?
Not given you a hard time; STOP and answer the questions. Correct the items above, THEN scan the car.
Are you a member of the UK Crossfire club? Maybe someone there can help.