usb problem & clean restore

Hello.
I purchased the 32GB fire phone and I'm very satisfied with it (on rhe cm,,,)
But
It has a hardware problem,
When the USB cable is moving a bit the phone is disconnecting from pc / charging
I tried six different cables....
does any one else experience this problem?

so
I need to return it,
After receiving the device I updated it to 4.6.1
I installed:
kingroot
safestrap
cm
gapps
supersu

I dont have any backups
Now before I give it back, I need to return it to the previous state with a clean fire os

how do I do it??

thanks