heres how to downgrade i9300 from 4.3 t0 4.1.2

[lolly_pop]

hi, I needed to "repair" imei on a galaxy s3 with factory 4.3 software .
without reading up, I know now that the modem is somehow tied in with the baseband and you get reception errors afterwards.

sooo... after searching 100's of sites I finally managed it.

so this is exactly what I did, im not saying its right but its worked for me !

1) downloaded "I9300XXELLA_I9300OXFELL1_XEH VER 4.1.2" from nspro support site and flashed it to my s3.
2) used nspro to "repair" my imei number.
3) phone rebooted but signal dropped in and out.
4) used odin to flash "modem_RIL_CWM_I9300XXELLA" file to phone from [REF] Galaxy S3 RIL+Modem CWM Flashable Collection - xda-developers
5) flashed "I9300_IMEI_Baseband_Repair" from nspro support area to phone.
6) phone rebooted with yellow writing test screen as expected !
7) repaired imei again using nspro.
8) realised that step 2 was a complete waste of time as I had to do it after step 6 anyway hahaha
9) held volume up/power and home to enter recovery screen and did full factory reset and also reset cache
10 rebooted and phone has full signal and keeps it !

so that's my method, thought it might help someone, please feel free to comment

lolly_pop

[debeliamark]

Originally Posted by lolly_pop

hi, I needed to "repair" imei on a galaxy s3 with factory 4.3 software .
without reading up, I know now that the modem is somehow tied in with the baseband and you get reception errors afterwards.

sooo... after searching 100's of sites I finally managed it.

so this is exactly what I did, im not saying its right but its worked for me !

1) downloaded "I9300XXELLA_I9300OXFELL1_XEH VER 4.1.2" from nspro support site and flashed it to my s3.
2) used nspro to "repair" my imei number.
3) phone rebooted but signal dropped in and out.
4) used odin to flash "modem_RIL_CWM_I9300XXELLA" file to phone from [REF] Galaxy S3 RIL+Modem CWM Flashable Collection - xda-developers
5) flashed "I9300_IMEI_Baseband_Repair" from nspro support area to phone.
6) phone rebooted with yellow writing test screen as expected !
7) repaired imei again using nspro.
8) realised that step 2 was a complete waste of time as I had to do it after step 6 anyway hahaha
9) held volume up/power and home to enter recovery screen and did full factory reset and also reset cache
10 rebooted and phone has full signal and keeps it !

so that's my method, thought it might help someone, please feel free to comment

lolly_pop

on step 4: Odin to flash CWM flashable file?

[lolly_pop]

Yes mate, I tried many times to flash it via the memory card but kept getting "file signature verification failed"
So flashed it with odin and it passed !

[debeliamark]

Any way ... tested ... you can do this easy...

xx. downgrade via NsPro to 4.1.2
xxx. Go to Factory Recovery and wipe data partition.
xxxx. Repar IMEI ( and SN ) after this ... / seem 4.3 translate security units to another memory allocation, but current Samsung tools do not catch it ( and restore it ) in downgrade operations / you must repair IMEI... NsPro work just fine ... TESTED!!!

WBR, DebeliaMark, BG\

P.S. All the best to C.B. aka Elco for his hard work last years - i wish him all the best and let be so smart and bright like till now. Happy new 2014, Elco!

[lolly_pop]

Originally Posted by debeliamark

Any way ... tested ... you can do this easy...

xx. downgrade via NsPro to 4.1.2
xxx. Go to Factory Recovery and wipe data partition.
xxxx. Repar IMEI ( and SN ) after this ... / seem 4.3 translate security units to another memory allocation, but current Samsung tools do not catch it ( and restore it ) in downgrade operations / you must repair IMEI... NsPro work just fine ... TESTED!!!

WBR, DebeliaMark, BG\

P.S. All the best to C.B. aka Elco for his hard work last years - i wish him all the best and let be so smart and bright like till now. Happy new 2014, Elco!

Hense the line" so this is exactly what I did, im not saying its right but it worked for me "

[Spalato]

I downgraded to 4.1.1 and repaired serial number and imei... phone works fine, has network...

Then I updated to 4.1.2 an imei is still the same and phone sees network but every time I try to make a call, phone says "not registered on network"

Any solution?


.

[lolly_pop]

Originally Posted by Spalato

I downgraded to 4.1.1 and repaired serial number and imei... phone works fine, has network...

Then I updated to 4.1.2 an imei is still the same and phone sees network but every time I try to make a call, phone says "not registered on network"

Any solution?


.

At a guess mate, I would start fresh and use my guide at the top of this post. Ive done it 4 times and its perfect every time.
Good luck

[theunlockpros76]

You do realize that you only need flash the modem and not the whole rom. Then flash the original modem back afterwards.

[lolly_pop]

Originally Posted by theunlockpros76

You do realize that you only need flash the modem and not the whole rom. Then flash the original modem back afterwards.

In his case I agree mate but my guide is how to downgrade from 4.3 to 4.1.2 ?

When I originally did mine I wasn't sure which modem went with which rom so thars why I said to start fresh because at least then he would know for sure if he starts from scratch and uses the links ive posted hes following a tried and trusted method ?

[Spalato]

I downgraded it to 4.1.1 and repaired imei and serial. Phone worked

Then updated to 4.1.2 and no network. Repaired imei an serial. Phone worked

Then updated to 4.2.2 and no network. Repaired imei an serial. Phone worked

Strange

Never had this situation that after every update, I had to repair imei and serial to make the phone work...

Will not update to 4.3 because I can't repair imei and serial in 4.3

.

[shine123]

4) used odin to flash "modem_RIL_CWM_I9300XXELLA" file to phone

Can you please tell me how to do this

Thanks in Advance

[lolly_pop]

Originally Posted by shine123

4) used odin to flash "modem_RIL_CWM_I9300XXELLA" file to phone

Can you please tell me how to do this

Thanks in Advance

Go to goggle and download the latest version of odin, extract it if its zipped, make sure usb debugging is enabled on your phone. Put phone into download mode, plug usb lead into phone and laptop.
Start odin and make sure phone is detected as a port number.
Click the phone tab, select the mod ril cwm file you should have already downloaded either.
Click go and its done.

One thing I did miss out on the how to, after flashing new 4.1.2 firmware the Samsung start screen will loop ! You need to do a full factory reset to make it boot properly before doing anything else.
You will also need to re enable udb debugging.

Good luck mate

[shine123]

thanks lolly_pop
that worked

[jhuds2004]

I9300_IMEI_Baseband_Repair

cant find this in support area ???

[theangrycrow]

I'm still trying to get an I9300 unlocked and pointers in the right place please