12. (10 points) A mechanism lock is shown in the figure, with a total of nine buttons including the Eight Trigrams and Taiji. After pressing any four of these buttons in sequence (once a button is pressed, it cannot be pressed again), the lock will open if the sequence matches the correct one; otherwise, the mechanism will reset to its initial state. It is known that before pressing Taiji, two opposite trigram buttons (such as Qian and Kun, or Xiong and Gen in the figure) cannot be pressed consecutively, and there is only one correct sequence. How many attempts at most are needed to open this mechanism lock?

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【Analysis】From nine buttons, pressing 4 in sequence, there are $9 \times 8 \times 7=3024$ (ways). Among them, the first two being opposite have $8 \times 1$ $\times 7 \times 6=336$ (ways), the middle two being opposite and the first step not being Taiji have $8 \times 6 \times 1 \times 6=288$ (ways), the last two being opposite, the first two not being opposite and not being Taiji have $8 \times 6 \times 4 \times 1=192$ (ways). Finally, sum them up.

【Solution】Solution: According to the analysis, from nine buttons, pressing 4 in sequence, there are $9 \times 8 \times 7=3024$ (ways); among them, the first two being opposite have $8 \times 1 \times 7 \times 6=336$ (ways);

the middle two being opposite and the first step not being Taiji have $8 \times 6 \times 1 \times 6=288$ (ways);
the last two being opposite, the first two not being opposite and not being Taiji have $8 \times 6 \times 4 \times 1=192$ (ways);
Therefore, all possible ways to press are: $3024-336-288-192=2208$ (ways).
That is, at most 2208 attempts are needed.
The answer is: 2208.