Chosen Solution
Someone offered to sell me an iPhone 7 for $40. The WiFi is greyed out and the frame is bent. Is it fixable or is that a board level issue? Should I buy it? I think it’s worth the money in parts alone as the screen isn’t cracked.
There’s no way to tell before opening up the phone and closely inspecting condition, but as you noticed yourself price is so low that it would be a good buy in any case.
If the wifi is greyed out it will be the wifi chip. As you mentioned the phone has been bent. This repair is not easy as the wifi chip has underfill around and under it. Usually some pads come off when removing the chip, these need to be rebuilt or traces run. If you need to install a new wifi chip you will also have to remove the nand and use a programmer to unbind the wifi address. One thing you can try is putting pressure on the wifi chip and see if it gets enabled if you are lucky and it does you can try and put a shim on the other side of the board to match the pressure point region. I would purchase the phone at that price.
Greyed out wifi is only fixable at a microsoldering level. Most of the time it will end up costing too much to repair as in $180+ or not being fixable.
