I know of no rigid rules regarding bullet points and how to punctuate them. Because of that, I defer to two principles. One is consistency. The other is the effect on the page, that is, the visual element.
Generally, if the bullet points are lengthy, which they usually are if used in posts on this site, all grammar and punctuation rules apply. The bullet points are complete thoughts, so they should be punctuated as such. If the bullet points are fragments, end stops may be used but aren’t required. The key is consistency. If one or two of the bullet points use end stops, the others must as well. The only other option is to remove the end stops so that none of the bullet points use them.
Sometimes, though, it’s hard to decide if the bullet points should or should not have end stops. In that case, I advise looking at the bullet points as they will appear in the post or on the slide. Do the end stops cause a reader to stumble before continuing onto the next thought? Do they appear too heavy-handed or staccato? If so, it’s best to remove the offending end stops and to leave the bullet points open-ended. If, however, the end stops contribute to understanding and don’t overwhelm the page or the viewer, they should remain.
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