How to remove and refit the EMI shields?

Hello guys,

I have to open the EMI shields on my iPhone 4 logicboard to clean the connections. On Youtube, I watched some videos but I don't get it, how to open and refit the shields? In the videos, the people use an hotair-workstation. The shields

disappear by themselves. But can I plug in the shields after cleaning or is it impossible, so that I have to buy new shields?

The shields are not cheap and I also have to buy an hotair-workstation.

Can anyone give an advise?