S3 Stuck on Samsung Logo After Reset

[starfleetgrrrl]

I wiped everything from my S3 so I could give it to my sister as a temp phone and now it's stuck on the Samsung logo. I've done most everything I've read about online. I'm not very tech savvy, but I'm worried about installing stock firmware because this phone was unlocked so I could use a T-Mobile sim in it. I'm not sure if that would mess anything up since my sister has the same sim card I do.
Any help would be awesome!

 

[Golfdriver97]

Welcome to the forums. Have you tried rebooting into recovery and doing another reset?

From my G4
Android Central Ambassador Team Leader

 

[starfleetgrrrl]

Yes! I've done both of these things. Multiple times actually.

 

[spagman]

After the factory reset you have to wait for a few minutes... Give it up to 10-15 minutes.

Is your model the I747?
Do you know what bootloader was on the phone?

Was it Rommed / rooted with custom recovery?

 

[starfleetgrrrl]

It is the I747 and I never rooted it. I don't know what bootloader was on it.