Positive out of a negative

Hello all so after some advice.

Long story short i dropped my uninsured iphone6s and even though i had a case i didnt have a screen protector (amateur mistake number 1) and the screen was cracked. This slowly got worse with it starting off as a thin long crack down the screen that slowly became little blots of black ink and now can basically no longer see the screen at all. However the touchscreen functionality has not been affected.

Now a week on from this i was walking down the high street about 8.30 when a panicked looking man approached me offering me his iphone6s saying he desperately needed the money quickly and was willing to sell me his working iphone6s for "£150 here and now". Of course my first thought was this is to good to be true and sounded a bit too dodgy, but after inspecting the phone could clearly see it worked and was in better condition than my phone (regardless of the crack and inked screen!)..to provide a bit more context, and slightly justify my actions, i was on my way home from work drinks so was a lil tipsy and started thinking this was just some great luck and a funny story to add to the evening. So i thought bugger it why not! Also saves me trying to repair the old one i could just transfer my sim from the old phone and hey presto working phone again. I also thought i could eventually pay the £100quid to get the screen repaired and with a £250 outlay i'd have two working iphones!

So i agree (amateur mistake no 2)...i give him the cash and he hands me the phone and we both "happily" head off in our own journeys. Its not until i get home and turn the phone back on and with shock (but an uneasy feeling of i knew it) the phone comes up with a message saying "iphone is disabled - connect to itunes)" .... so this DEFINATELY didnt happen with the one he showed me (head now in hands).

After doing a lot of research i have come to the conclusion there is nothing i can do about the phone, serves me right i guess and im over it (kind of). However can i somehow still get something out of this situation by using as many parts from the locked phone phone i bought to repair my actual phone? My phone is actually pretty fine except the screen...

Thoughts and advice are welcome!!!

Thanks in advance.