ok, so I had a fried SP230. I downloaded an SD bootable *.nb0 files (the link is available in this forum) and at least got the thing running again.
However, these were PPC4100 files, so the PDA functions, but the phone is dead.
So, please someone who has SP230, please upload Your ROM

You can get the ROM file by doing following:
1. Download OSImageTool from
http://wiki.xda-developers.com/wiki/XDAtools
2. Run the tool and choose
a) Source: Device memory
b) Destination: push '...' icon on the right and put the enter name like SP230.nb1 (nb1 is important, otherwise OSImageToll won't work).
3. Upload the resulting file eg. to yahoo folders.

I've checked resulting files and there's no problem extracting the new ROM from the *.nb1 file, just a little tweaking needed, which I'll be happily reporting back to You guys. Just get someone to upload that SP230 ROM... PLEASE!