iPhone 5 logic board related trouble. Need a solution desperately! :(

I'm kind of in a sticky situation with my Apple iPhone 5 and I'm stuck at a dead end with no more options in front of me. Please tell me what I can do.

My phone was not charging and not booting past Apple logo when connected to Lightning cable. So I first tried Restore-Update-Restore thinking it might be some software issue. But the problem still persisted so I figured it might be some hardware issue and after some Internet research I zeroed in on the U2 IC. I opened up my phone to see if changing the IC is something I can do as I've been conducting all prior repairs on my phone such as changing damaged LCD, irresponsive power button, non-functional front-camera etc by myself by ordering parts off of eBay. But in the process I ended up physically damaging the U2 IC and slightly, the area on the logic board where the U2 IC connects. I didn't wanna further mess anything up or take a risk so I sent my phone to a 3rd-party professional iPhone service center. They did a diagnosis on my phone and said that my phone is apparently irreparable by them cause even after they changed the U2 IC the logic board is not able to read it due to damage of the pins or whatever. They said the only way to get my phone repaired was to change the logic board which they don't do by themselves. So I looked on eBay and found completely bare logic boards with no IC's or components installed on them for sale and at very low costs. I then contacted the service center again and asked them if I provided them with this logic board can they remove all the components off of my old logic board and attach them to the new board and also install a new U2 IC so that my phone is then fully repaired to which they said that they can remove IC's from my old board and place them on a new board but that does not include the processor chip and the baseband chip as they cannot remove or do anything with those two chips unfortunately. Is it really true that only Apple can do any modifications or repairs with the processor and baseband chips as told to me by the guys at the service center or is it just something to do with their policy? Can all the IC's and other components be removed from one logic board and be reattached to another without losing any functionality? They said they can do what I suggested if I provide them with a logic board which has at least the processor and baseband chips installed on them or a logic board from an old iPhone 5 or something. If I have to purchase a logic board which has a network lock and/or iCloud activation lock I am willing to do so provided that I can use some software/application or any other way to remove the lock(s).

I NEED to get my iPhone repaired so bad! Please suggest me the cheapest and best possible solutions for my dead iPhone.

I'm also attaching pictures of the damaged area for clarity.

Thanks a lot guys.