[Q] Desperately need help getting unlock code for SIM. I have no idea what I'm doing. topic

Ok, so, here's my research progress so far:
1. My phone is locked to T-Mobile.
2. My friend wants to use it with her At&t SIM
3. Requires unlock code.
4. Call T-Mobile to ask, they tell me I have to ask Walmart Family Mobile cause that's where I got the prepaid SIM for the phone.
5. Last time I used the Family Mobile was like, 2 years ago. I called and they said I'd be eligible for the unlock code if I paid my back dues. They totaled around 9 (no thanks).
6. Try to use the two actually free services online that provide the unlock code if you provide the MEI (waded through leagues of "FREE! but actually pay ").
7. Internet says something about unlock code being in a BAK file or something, requires rooting.
8. Rooted, installed Cyanogenmod.
9. A couple forums say something about doing ESF backup and doing some copypaste with a file in the backup.
10. Tried like 3 different ESF backup apps/programs, everytime I still can't find ESF folder/files anywhere with my computer.

Please help, I've been wondering a maze for the past 6 hours.

Phone model SGH-T769