Blackberry 8520 Error 552 problem

[TFTC]

My Blackberry Curve 8520 started showing Reload Software: 552 on the screen (thats after ive installed Google Sync and it kept showing error messages). After going through BB forums I found the option to recover the situation outlined on this link: http://supportforums.blackberry.com/t5/BlackBerry-Tour-9630/Reload-Software-552/m-p/354083. I started the BB Desktop Manager and connected the phone with the battery out but there is no "Application Loader" on the UI. rather a Pop out Message is appearing saying "Blackberry Desktop Software cannot communicate with the connected device" and its giving me the option to Retry, Update or Close. Retry brings me to the original screen but when I click Update it searches for a while then it says "There are no Blackberry device Software updates available" but I have installed v5.0.0.592 for Blackberry Curve 8520 which is meant for MTN. I am using BB Desktop Software v6.0.0.43. Thanks in advance