[Galaxy S 4 Q&A, Help & Troubleshooting] seitsme:
hi all,

I decided to do my first post as i am stuck with something i am not sure how to rectify as a newbie in the android world but not newbie in the computer world.

I bought a samsung s4 GT-i9506 secondhand phone with damaged usb port thinking to repair it and try my skills for interest above all.

So got the port replaced and mobile charges ok now, i see the device working. battery is OK.

I think the device is Samsung Galaxy S4, and UNLOCKED possibly 2013 model GT-i9506 Black.

I found on the web some other codes like VDS or Shv-e330s-510 but not sure if these mean GTi9506 or are similar.

I found how to wipe - reset to factory, did that and did all updates to the phone. I dont know what OS was previously on the phone.

I then found the IMEI and paid via ebay to do a device or carrier check and got the following results including some other i add by myself.

I give all the info further down.

So, i tried to put a sim card and got error with SIM network unlock PIN window.

I added sim card, local card without subscription Lyca or comviq for above issue.

I dont know the pin and i click dismiss instead of unlock.

So, i need to unlock the networ i understand.

The paid check said unlocked so not sure what is going on with the phone at this stage.

After searching online I went in networks and did a search. I got results as below:

Telenor SE

Telenor SE

Tele2

3 SE

Telia S

So no Lyca or Comviq listed or not sure if ie Telia handles Lyca (I think Estonian company)

as i see Telia signal on the mobile from time to time, using the Lyca sim card.

I then found a video how to enter the service menu to do unlock of the network for free.

It works when i do the 0011 dial with star and hash keys combination, but does not accept

entering key values ie 1 etc to bring the next menu up etc. So it stays in the first service mode screen

which says (some items change values while this mode is on)

RRC:idle band8

mcc-mnc 240-02

rx 2398 RI -76, CID 780353

tx 2713 PSC 476

eclo -5 RSCP -81

speechver FR FR FR

L1 PCH_sleep

drx cycle 64

sib19 is received

therm 0 LNA 0

service Limited

PA state 0 APT, HDET 0

imei certi NA

-----

So i abandoned this operation and tried to follow other videos ie to root device

and run an app, i forgot its name, found in XDA as apk file that does this unlocking as well (may work)

as could not find it in google play store.

I downloaded a root checker app and checked device. It said may not be rooted or need to grant SU permissions.

I got another root checker and said that device may not be rooted ok, but i guess could be same issue as above.

I also read that samsung disable the service mode and maybe my update is not allowing this mode to work and needs root

or flashing earlier OS versions which i have no clue how to find and apply - i have no instructions at all.

Then i tried to find free root apps but no luck as not sure what you do after that and where. So i stopped here and thought to

ask in the forums.

So, which is the best way to free fix my network problem on this oldie phone...

How can i downgrade and or flash to an older android version that will allow me to run the service mode OK etc. what do i need for that.

Platforms and software pc or mac.

I have a soldering iron and screwdrivers and may do some soldering if is possible to my skills.

Mobile info from about device menu included below.

-----

basedand i9506xxudpL1

kernel version 3.4.0-6069869

dpi@swddd5616#1

thu dec 1 13:43:16 KST 2016

build no. LRXX22c.I9506xxSDPL2

SE for android status

enforcing

SEPF_GT-i9506_5.0.1-1_0039

thu dec 1 13:45:59 KST 2016

KNOX version 2.3

standard sdk 5.3.0

premium sdk 2.3.0

customisation sdk 2.0.0

container 2.3.0

cep 2.0.1

enterprise billing 1.0.0

SE for android 2.3.0

sso 2.1.1

TIMA 2.0

VPN 2.2.0

-------------some other info i added not from about device menu----

Android v5.0.1, SD card.

STORAGE hdd: 16GB total. about 10GB free with latest OS installed updated

STORAGE microSD card max: 64GB

SIM CARD type: Micro (not nano) Medium size type

SN= RF8DC05A6AE

SSN= -i9506GSMH

FCC ID= A3LGTi9506

from the paid check i got

Model Info: MOBILE GT-i9506 BLACK VDS

Serial Number: RF8DC05A6AE DO (different from SN above has extra two letters at the end)

Number: 8202869406(C4F0-05)

Model Number: GT-I9506ZKAVDS

Model Name: GT-I9506

Model Desc: Galaxy S4

Warranty Status: Warranty Expired

Production Date: 01-12-2013

Warranty Until: 10-12-2014

Manufacturer: Samsung Electronics Vietnam (SEV), Bac Ninh City

Carrier: Sweden Unlocked

Sold By: Sweden / 11 December 2013

Blacklist status: Clean

----finaly the end....

I use english language menus for operating the phone

thanks for reading :D