Originally Posted by PvtJoker
Thank you, Quantumrand!
I have started a thread on Google Mobile Help to outline my specific issue, some more users with the same problem replied, but no reaction from Google - I am not sure they are even aware of it, let alone they are trying to solve it... I feel like I am "rolling back"to my good old SE P910i (6,5 yrs old, indeed and still kicking), I will at least be able to make/receive the calls and SMS... So much for the Android, used it for 6 months...
My baseband version seems to be I9020XXKI1, do you think the same GB installation file should be applicable as for the I9020T or I9023?
Since you installed the ICS update manually using the link in the OP, it'll say I9020XXKI1 (possibly I9023XXKI1, but I don't have an I9023, so I can't say for certain) no matter what, since that's the radio the update flashed to your device. The fact that the update let you install it at all suggests that you do indeed have either the I9020T or I9023.
The only way you could flash the current 2.3.6 to 4.0.3 update on an I9020A would be if you had a rooted phone with custom recovery image, which I'm assuming you don't.
That stock 2.3.6 update I linked you in my last post should almost definitely be for your device. What I don't know is whether or not it will actually let you install it coming from 4.0.3 with the stock recovery image. If it does let you install it, there's very little chance it will break your phone. If it doesn't let you install it, it'll give you an error before making any changes and stop the installation automatically.
If you do attempt to roll back using that file, let me know how it goes. It will be useful information.