the adoption of the symbolic script and meaning
No. This would not work, for essentially the same reason that Japanese does not use kanji (borrowed hanzi) exclusively, augmenting it with a syllabary. Chinese is very heavily isolating, so for the most part you can get by with one character = one word (sometimes two characters = one word). Grammatical marking is all done with separate words, and thus separate characters. Japanese does not work like this, and neither does Aztec.
Actual historical Aztec writing actually works rather a lot like Japanese--there are native logograms, similar in function to hanzi, augmented by syllabic components. Much like early hieroglyphs, the phonetic component of Aztec writing was still based on the rebus principle, and had not developed into a full-fledged, independent syllabary like hiragana and katakana.
using the characters for syllabic writing
This is possible, but not particularly likely. The Aztec already used their own logograms for syllabic writing (see above). Adopting the more abstract and simpler Chinese hanzi might seem like a good idea to reduce the effort of writing relatively complex native Aztec symbols, but the phonologies of Aztec and Chinese are sufficiently different that the set of syllables available to write with Chinese characters that Aztecs would actually find useful is not particularly large.
a mix of the two much like Japanese
That would be the most likely outcome. If the Chinese explorers had sufficient cultural power, such that it is seen as prestigious to copy Chinese things, then hanzi could come to be used for root words, with native symbols being developed into an augmenting syllabary for fully dual semantic-phonetic writing, like heiroglyphics, or for indicating grammatical morphemes and native words for which no Chinese equivalent is available. The greater utility of Chinese hanzi over the complex native glyphs would not, however, be a sufficient force to get the Aztecs to replace their native writing system on their own. The Chinese explorers, however, might very well come up with a mixed logographic / syllabic transcription system for Aztec for their own use based entirely on Chinese characters, regardless of their standing in Aztec society.