unloack diagram

Hello,

Me and my colleague were sharing one model. and he forgot to release, now I want to continue with the same model.

As I am opening this diagram, it shows The diagram in read only .More info..

I clicked on More info dialog box appear and there is a button Unblock Diagram

Q : If I click on Unlock Diagram than can I see all the changes are done by my colleague or not ?

Q : What the problem can be occur if I unlock the diagram?

Q: Should I do or not do?

or

Q: is there any other way to unlock diagram.

Thanks