I had completed the task 2 p.m.

Hi, everyone.

I learned that past perfect tense can be used to shown an event happened before a reference point in the past.

1) I had completed the task by 2pm.
2) I had completed the task at 2pm.

Does sentence 1 mean the task was complete not later than 2pm or before 2pm when past perfect tense is used?
Is the sentence 2 grammatically correct and does it have the same meaning as sentence 1?