I am not sure I follow your logic on the output and am concerned that you may you have oversimplified your problem in your post.
based on what you have provided...here is one way to provide what you have requested
SELECT
minv_code
, alert_msg
, alert_time
FROM @table
ORDER BY minv_code,
CASE WHEN alert_msg ='Meter' THEN 1
WHEN alert_msg = 'Tamper' THEN 2
WHEN alert_msg = 'Reverse' THEN 3
ELSE 0
END
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you can lead a user to data....but you cannot make them think
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