I was in your shoes a few weeks ago. I've never done hot air work before so ordered a Yihua rework station and a few IC402 replacements as well and went to town. I started on a pretty low heat setting (500F I think) and held it on the chip for maybe 10 seconds. The whole board and all its components heat up quite a bit in the process, so I was very conservative with the heat application to try and prevent frying anything else on the board. That didn't work so I let the board cool off and then upped the heat. I repeated this process probably 10 times before I was getting to a pretty high heat setting (maybe around 900F) and then was really scared I was going to overheat other components, but the solder still wouldn't melt. Eventually I just went yolo on it with a high heat setting and held it there for longer than I was comfortable with and got the chip to melt off. I think the dual ground planes really pull the heat away from the component. Definitely wait until it's floating on the melted solder to pull it off and don't try to pry it at all or you'll pull the traces off the board and then you have a whole other set of problems.
I just used a soldering iron and the residual solder on the pads to reattach the new chip, adding a tiny bit of new solder where it seemed necessary. Apparently I didn't fry anything cause it's been working fine ever since. Was still pretty nerve-wracking though.
And for the diode I just used the soldering iron. Blasting that area with the hot air gun seemed like a bad idea.
Best of luck!
Brad
