[SOLVED] K800i 5-6 Buttons not working.

I was playing java game and buttons stops working. All functions works fine, but buttons...
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P.S. FW Reflash didn't help.

Probably there is a contact error between keypad and mainboard. Take apart the phone and clean that connector pair. But only do this if you have at least a little experience with electronic devices!!!

If you are unlucky it could be keypad membrane gone you can get them pretty cheap on ebay, but I agree with simox Check the contact are joined. Here a page show you how to Dismantle your k800i.
Sony Ericsson K800i disassembly

Everything was fine except oxidation, my father is fixer of electronic and mechanic devices, like TV, Audio, Video and many other devices so with Sony Ericsson K800i disassembly we haven't any problems, he cleaned like I say "oxidation", which was on and near connectors.
P.S. it looks like white color spots, most of reason is damp. Became nonconducting.
simox and Loz - thanks for help.