Help what is wrong with my phone please help?

[5315153531401]

So I live in Mexico and my friend from USA gave me their phone (samsung s6) with sim card and all. After he got back to the states he bought a new phone he got a new sim card and so obviously the one in my phone stopped working, so i went to some shop here and they said to give them three days to make it work because my sim card i bought is a Telcel one and my friend was with AT&T. anyways after getting my phone back i noticed there is a circle with a line through it instead of signal bars and I checked the do not disturb feature and that was off. I tried making a call but it tells me mobile network not available.. basically the guy from shop said he couldn't get it to work... I think he may have rooted my phone because i downloaded root checker through wifi on play store and it says " root access is not properly installed in this device" anyways i did a hard reset and it still says that and sometimes when i mess with the settings it gives me an error message saying "unauthorized actions have been detected restart your phone to undo any unauthorized actions"... I thought maybe it was a carrier unlock issue but now i fear its something worse because I checked my phone and the imei said unknown...how do i even begin fixing this i only have access to a computer and wifi what do i do to fix?

 

[mikedt]

No IMEI, that sounds like the guy from shop screwed it up, and the guy really needs to put right whatever it was he did.

No IMEI and no service often means the baseband firmware has been corrupted or damaged by whatever the rooting did. Basically the phone needs to be re-flashed with the original manufacturer ROM. It sounds like the guy in the shop is completely incompetent. You should be able to find the files it needs and instructions at needrom.com.

 

[5315153531401]

No IMEI, that sounds like the guy from shop screwed it up, and the guy really needs to put right whatever it was he did.

No IMEI and no service often means the baseband firmware has been corrupted or damaged by whatever the rooting did. Basically the phone needs to be re-flashed with the original manufacturer ROM. It sounds like the guy in the shop is completely incompetent. You should be able to find the files it needs and instructions at needrom.com.

So how do i reflash it after downloading it from needrom.com? Also i cant seem to find the original from that website...

 

[mikedt]

As it's a Samsung, I now think maybe be better finding the correct original firmware here. https://www.sammobile.com/firmwares/ search for the model number of your particular S6, AT&T version? And I believe it has to be flashed with Odin using a PC. Exact details I don't know, I don't have a Samsung device. However should be details on that site, and likely there's YouTube videos demonstrating what needs to be done. And hopefully this should get the baseband working again, restoring the IMEI.

 

[Slug]

Topic moved to device-specific sub-forum. The folks here should be able to guide you as to the best solution.

 

[5315153531401]

As it's a Samsung, I now think maybe be better finding the correct original firmware here. https://www.sammobile.com/firmwares/ search for the model number of your particular S6, AT&T version? And I believe it has to be flashed with Odin using a PC. Exact details I don't know, I don't have a Samsung device. However should be details on that site, and likely there's YouTube videos demonstrating what needs to be done. And hopefully this should get the baseband working again, restoring the IMEI.

So I downloaded the g20A fimware (the one i needed) and managed to connect my phone to Odin3 (had to download kies) but whenever I click on start it tells me it failed.... this is the log from odin3 I clicked on AP and then selected the firmware and once i hit start it failed and this is the log i got i am using odin3 (V.3.12.3) .. how do i fix this?? or get passed this? I hear a lot of people fail at hidden.img but i did not even get that far..hopefully that wont be an issue too..would really appreciate any help (P.S phone is a samsung galaxy s6)
<ID:0/003> Added!!
<OSM> Enter CS for MD5..Do not unplug the cable..
<OSM> Binary Check MD5.. Do not unplug the cable..
<OSM> Please wait..
<OSM> Checking MD5 finished Sucessfully..
<OSM> Leave CS..
<ID:0/003> File analysis..
<ID:0/003> SetupConnection..
<ID:0/003> Initialzation..
<ID:0/003> Get PIT for mapping..
<ID:0/003> Firmware update start..
<ID:0/003> boot.img
<ID:0/003>
<ID:0/003> Complete(Write) operation failed.
<OSM> All threads completed. (succeed 0 / failed 1)