Maybe it will help some people. There is possibility to get
BIS back using Kaician's way to change language in x50. Here is his thread:
http://www.aximsite.com/boards/showthread.php?t=83668 .
I've just brought my
BIS in x50v back... If you've
lost your
BIS you can try to change ROM to Japanese and then back to English. I downgraded ROM to A02EN and changed to A01JA with header from A03EN. After hard reset (it takes a long time because of ROM formatting. In my case it was 20 minutes!! Be patient)I changed ROM to A03EN with header from A02JA and voila!
BIS is back. Be careful because you can brick your x50, and remember 2 facts: if something will go wrong you're out of warranty and your're doing it for your own responsibility. You can also try tool called psmformat. I haven't tried it but heard worked for a few people here in Poland. Good luck!