Is My iPhone 5 Dead??

Hello,

Three months ago i dropped my iPhone on the cement floor. it broke the LCD and digitizer assembly, also shattered the glass. I took it to a phone repair store and they tried twice to replace the screen on it, the second attempt was successful. $150 later i walked out the door, drove home and noticed my phone had a NAND error? so i shut it down and restored it. nothing happened! so i researched and tried many thins including:

-removing the front camera flex cable

-removing the front camera ic chip

-changing the battery

-changed the dock connector

-bought a new screen thinking that might be the case

I now have it to a point that it'll boot 5% of the time, the other 95% of the time it just shows boots to the apple logo (not a boot loop) i tried dfu restoring and everything, now when i restore i get a error in iTunes 4013. sometimes it will restore a little ways until their is a spinning icon, and then it freezes. whenever the phone decides to turn on, i can use it all i want, but if i let it go to sleep it shuts off by itself and goes into the stupid boot screen that i mentioned before.

Any help is appreciated as wouldn't like to buy a new phone!!