Yes, I recomend you to follow this step by step guide to remove the logic board, don´t be afraid, it´s not that hard. Just keep an eye on those flex cables, I had to replace one 😐
http://www.ifixit.com/Guide/Installing+iPhone+4S+Logic+Board/7283/1
I just took a picture to show you what area I heated up. This is the wifi chip (actually a sticker on the chip but you can leave it alone)

I had to do it twice, first time I was too scared and only heated it up for about 20 seconds. The wifi worked for only an hour and then greyed out again. So I disassembled it again and heeated it up for about 1,5-2 minutes and it was really, really hot. I wondered if it ever will power on again but on the other side - 211 EUR repair was too much and and an Iphone without wifi is almost useless to me.
If you decide to try it out, let me (us) know if it worked.
Edit: Some kind of "proof pic", taken 4 Minutes ago.
