Start here : Flash your phone and How to apply or remove patch using SETool 2 Lite - Top Sony Forums
and use the following files;
K800_R8BF003_MAIN_GENERIC_WI_RED52
K800_R8BF003_FS_EUROPE_2_RED52
HB1-06_Gen_CDA102568_11_R6A_GENERIC_EUROPE_2
if this doesn;t help then it is probably a hardware fault i.e LCD damage, changing LCD will solve your problem




