Can you help me with these English sentences and tenses?

Some days ago, I went to a mobile shopee. I read there a sentennce written on mobile box.

Don’t open the box if the seal is broken—I know it’s a passive voice sentence & simple present tense)

But if we make the above sentence by putting “has” instead “is” then is it correct?. Does it mean same?.

My second question is there was a sentence written on a board in a hotel,

If you had a good time with ABC (hotel’s name), Ring the bell.

then, what does this following sentence mean to you?

If you have enjoyed a good time with ABC, Ring the bell.

Do these sentences mean same to you?

My third sentence makes me garbled is,

Your mentioned issue is resolved. (I know it’s a simple present & passive voice sentence).

My question is, can we write the same sentence like this,

Your mentioned issue has/has been resolved.—- Is it mandatory to write the time of activity when it was finished?.

I mean,

Your mentioned issue has/has been resolved in the afternoon itself.

I am totally confused about simple present & present perfect tense.

Can anybody you clear up my doubts?