Hi.

i would like to try other way for same

I did it several times with a soldering iron. I have twisted a wire around the iron to get a second, much sharper tip. I also sharpend the end of the wire. With a soldering iron tuned like that i soldered the components under a stereo lens basically like normal components. I know this method is a bit extreme but i am not familiar with hot air ;-)

You also should use flux. I have liquid one that sucks itself under the components. Its called FL 88 FLUXI. I am very happy with that.

A multimeter is not the right tool for testing for shorts. It sends a current through the parts. As the parts are soldered into a circuit you can not really distinguish between low impedance components and real shorts and depending on the multimeter quality you might ruin parts. You have no AVR here, its a very sensitive HF circuit, don't forget that. I think you better inspect it visually using a stereo lens.

Don't worry if you ruin some phones, thats normal. I think i ruined two phones before i could do it properly. You also should be familiar with SMD hand-soldering otherwise you won't have a chance.

After the mod do not use the phone for transmitting anymore as you might ruin the receiver then.

regards.
Philipp