To remove the PCM you need to remove the lower half of the dash under the coulumn, and the side trim on drivers side of dash, GEM module (the module with the coloured connectors) then the bracket around the PCM, once you can slide the PCM down, there is a security nut that has to be drilled/ground off..they don't make it easy!

Worth asking where you bought the coil pack from if you can try another.

As said though, the fault code with primary circuit which you had originally can not be ignored.