I found, from different site on the web, on how to downgrade the firmware of SE-P990i.
Here is a brief step:
1) Look for the firmware level you would like to have your unit be downgraded from R6E28. Here's the list -->
[Only Registered users can see links . Click Here To Register...] . Identify the CDA. (example if you want to downgrade it to old R3B01, you may choose CDA coming from Greece which is 162008/27)
2) Change or Debrand your unit to 162008/27 ( Here you can study on how to debrand P990i -->
[Only Registered users can see links . Click Here To Register...] ). Note: this task is very sensitive and tedious to do. If you made a mistake, you will end up a dead P990i unit.
3) Upgrade your P990i via Sonny Ericsson Upgrade Services (SEUS) twice. The 1st pass is to revert everything to default, 2nd pass is to finalize the upgrade (or downgrade to R3B01).
However,
I don't recommend you to do that because you need to do some homework to make this things work perfectly. We are not so sure on what firmware level the autofocus would work on the camera again. It's really not a smart thing to do, unless you have a lot of bucks in order to repair a dead P990i from SE service center.
I recommend you to bring the unit to the nearest Sony Ericsson Service Center. Explain to them your problem, have them fix or revert it back to old firmware. Do this even if your unit has or without warranty.
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