The places in the mall just replace whole parts and many do not do that very well. That is much different than exchanging components on the circuit board. Even Apple does not do stuff like that, they just toss it in the recycle bin.
I wouldn't bet on that. Where do you think the parts in refurbished iPhones come from? Apple wouldn't throw away several hundred dollars worth of parts just because it needs to be repaired. With the right tools and experience, it can be done.