John,
the blow-out shot is ok; however, something is strange. The template shot (the blown-out one) itself does not need to and normally will not appear as white, because that was shot with some other WB setting; that plays no role. However, this template has the WB coefficients R=1.03, G=1.0, B=0.95. There is nothing wrong with that, but how did you achieve this? Normally, i.e. if you shoot it with for example "daylight", you get some very different WB coefficients. Have you used Guillermo's method? Then you have already a relative good template, but you may be able to get a better one with the overexposed shot.
In other words, that WB setting, which was active when creating the blown out shot is suitable for ETTR (the 0.95 is not stellar, but ok).
I'm afraid you misunderstood some step; I rather explain it once more.
1. You create a shot, which will be used as WB template in the subsequent shots. It absolutely does not matter, with which WB setting you created the template shot (the totally overexposed one or the colorful one).
2. You declare that image as WB template through the function "Custom WB" (see page 66 of the manual). Select the function and select the image (the blown out one) and set it. Now the camera analyzes that image data, calculates and records the WB coefficients as "Custom WB".
There is an interesting note on page 67: if the exposure obtained in step 1 is way off, a correct white balance might not be obtained I don't know if this means that the camera will reject some templates, or that the result is not all right.
3. From now on, any time you select the WB "Custom" (this is not the function "Custom WB" but the big dial after you pressed the WB button), those WB coefficients will be used.
Make a shot of anything now, and upload that please.
If this works, you will get perfect WB coefficients and you don't need to do anything with Guillermo's method.
(I may go to bed in the meantime.)
