How to start with microsoldering on iPhone logic board

[extra22]

Hi!

First of all, thanks for letting me in to this forum!

I do some kind of iPhone repairs (cracked screen etc) and want to expand it with micrsoldering. I have basic understanding of soldering. But I feel like this is a whole new world to me. Have seen tons off youtube videos, but still I have some question that I hope you will help me on:

1. How do you test if a part is function or not? Do you use a multimeter and test, or do you just take the logic board under microscope and look for damage?

2. How to you know what method to fix that part? I see some just reflow the part, other rework it. Some solder the parts back into the board again, and some other just heat it from underside and then the part "falls" into palce.

3. Could anyone explain to me in detail step by step the process he is doing here: ?

Thanks for all the answers. Much apreciated 

[Yago]

Have a look at Dave's soldering tutorials, he has iron, hot air, and demonstrates "Chip Quick" low temperature solder videos.

There are links on the home page of this forum.