I was shooting with my Nikon n2020 yesterday, was outside for maybe an hour and a half, shot a full roll. I developed them today, and there are two shots at the end of the roll that showed up blank. The film advanced, but the shots were completely blank. Could this be caused by the batteries being too cold and the shutter not opening, but the film still advancing? Or something else?
It is possible. I would think an OVERALL drop in performance would be more indicative of battery failure. This time of year in Northern climes it never hurts to have a spare set in an inner pocket.
My guess would be the roll stopped short of the end for some reason, especially if there was enough power to rewind. That's if the negs are clear (little to no density). If they are completely dense, and I don't see how they would be by your description of what happened, that would be indicative of over exposure.
What shutter speed where you using? I had an instance a few years ago where the curtains on the M3 I was using at the time just got too sluggish from the cold. Anything I shot at 1/500th or 1/1000th came out blank. No batteries in that camera to be affected by the cold.
That would be the simple explanation. I would just be more cautious in the future. If you have good exposures later on, I would say a mild case of pilot error. Besides, that shutter sure can be quiet if you're not paying attention. If you have good battery power, I would doubt sluggish shutter on a N2020.