Flash it with these files:
MAIN : K310_R4EA031_MAIN_GENERIC_DO_RED49
FS : K310_R4EA031_FS_S_E_EUROPE_RED49
custpack : K310_GEN_CDA102576_3_R5A_GENERIC_S_E_EUROPE
they all are in the download area. use the search button before muffling out "but all I could get on google is"
This is Top Sony and not google