##778 Did not work - in a pickle now-HELP

[nano24]

I flashed my XV6900 last night and could not make calls. I tried *228, but did not work. So, I called VZ and they tried, but when dialing the ##778 to get into the programming menu, it dialed out instead of going into the menu.

Now they are sending me a replacement phone. Questions:
1. Has anyone had this issue?
2. Do I need to do anything to the phone I am sending back so they don't charge me for the replacement if they see I was flashing it?
3. Is there a way out of this so I can keep my phone?
4. I think the mistake I made was when I installed the unlocker, I let the Sprint customizations run (I was too late to stop it-aaargh). Is there a way to undo this?

Please help ASAP as they are sending a replacement today - will arrive tomorrow.