How to upgrade Galaxy S2 from 2.3.6 to jelly bean, Kies does not recognize device?

[AC Question]

How do I upgrade my Samsung Galaxy S2 to Jelly Bean?

The model is SGH-T989, baseband is T989UVLDH.
The device is not recognized by Kies 2.6.
I reinstalled the device driver, tried 3 computers, one XPsp3, one Win7 and Win8.1, different cables (including the original one) but no luck, Kies keeps complaining your device is not supported.
Tried Kies3 too.

Is there any way to upgrade this to jelly bean
without running a serous risk of bricking it ;-)

Thanks

 

[Rukbat]

Not updating (which leaves all your data intact), but there are some JB ROMs for the T989 at SamMobile Firmwares. Find the one for your country/carrier and flash it using Odin.