Must flash EROM and after flashing must flash Main -> then can turn on (this method only works on EROM CID52 phone).
If your EROM is CID53 cann't free.

Read here how to connect to XS++: USB Flash Driver Installation - Guide - Top Sony Forums
And here how to repair EROM: REPAIRING EROM GUIDES for most sonyericsson phones - Top Sony Forums