as u describe about your phone the rotating clock, its mean u have the software issue. Follow these steps.
1) download JL_cmdr .
2) Download BB desktop Manager.
3) download the software for ur blackberry 8520.
first of all run the blackberry desktop manager then connect your blackberry so that your system automatically load the drivers for ur blackberry.
then close the bb desktop software.
now run the JL-cmdr and select the wipe option from the list.
now ur phone will shows the error 507.
now close the jl- cmdr and open the blackberry desktop manager.
and connect ur device and pull out the battery then click on app loader
the phone will connect and automaticaly select its appropiate software
after the loading process start insert the battery.
when the phone completely updated disconnect ur phone
now ur phone is ready with the new software.
