'Fine' isn't an example of an open syllable. It's an example of the vowel-consonant-e syllable type (alternately called 'bossy e', 'magic e', 'sneaky e', 'silent e' or various other cutesy mnemonic terms).
'Hello' is comprised of two syllables - a closed syllable (hel) and an open syllable (lo).
There are six basic syllable types in English (although some break the double vowels down into two for a total of seven):
1. Open - no consonant on end, vowel is long.
Examples: me, and the second syllable in hello
2. Closed - ends with a consonant, has a short vowel sound.
Example: cat, hit, pot
3. Vowel-Consonant-
E (aka silent e, sneaky e, bossy e, etc.) - just as the pattern says, it's a vowel followed by a constant ending in the letter 'e'.
Examples: fine,cake,Pete
4. Vowel team - two vowels work together to produce one vowel sound.
Examples: steam, boil
5. R-controlled
- the letter r follows a vowel, and colors/controls/influences the vowel sound to where it's neither long nor short.
Examples: star, cord,skirt
6. Consonant-L-E - as the pattern says, the word ends with a consonant followed by the letter L and a final E.
Examples:table, bubble, circle
Some people make a distinction with the fourth pattern, and separate the diphthongs (two vowels blending into a new sound such as
boil, loud) from the digraphs (two vowels making one sound such as
meat, float) into a seventh syllable type. I'm not going to argue for or against that, but simply mention it so you're aware why you may see a list of seven syllable types instead of six.
All of those words have an open syllable, (type 1 on my list), followed by a closed syllable (type 2). You have to look at each syllable in a word, and apply the appropriate rule. The pronunciation rules govern only individual syllables, not the entire word (unless it's a one-syllable word).
It's not the same rule. None of those are open syllables. Those are all examples of the silent e (type 3) rule.
'Zero' is comprised of two open syllables, and rule 2 on my list applies to both of them, just as it does to the 2nd syllable in 'hello'.
I think your confusion may be a result of not looking at each individual syllable and recognizing that a multi-syllabic word may be comprised of different syllable types.