Can i do this

[Irvgotti]

i have a thunderbolt and a nexus. i dont use the thunderbolt. so can i activate it, get a replacement (by saying it has software issues) , and sell my new phone at full retail?

 

[Rukbat]

i have a thunderbolt and a nexus. i dont use the thunderbolt. so can i activate it, get a replacement (by saying it has software issues)

Only if it actually does have software issues, and only if those issues can't be fixed (assuming the phone is still under warranty).

and sell my new phone at full retail?

Not if you're still under contract for that phone. And if you aren't they won't replace the phone.

IOW - short answer - you can't do what you want.