
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
Given an arithmetic sequence $\{a_n\}$ where $d > 0$, $a_3a_7=-16$, and $a_2+a_8=0$, let $T_n=|a_1|+|a_2|+\ldots+|a_n|$. Find:  
(I) The general formula for $a_n$;  
(II) The value of $T_n$.

Present the answer in LaTex format: \boxed{Your answer}
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