I tried it again on another pc and this time it worked.
Here's the xs++ log:

12:43:48| XS++ v3.1 (Darwin) Ready !

12:43:48| Executed on Microsoft Windows XP

12:44:24|

12:44:24| Attempting to open the interface...

12:44:24|

12:44:24| TURN OFF PHONE!

12:44:24| Hold 'C' button on phone and connect phone NOW.

12:44:24| You have 30 seconds...

12:44:24|

12:44:29| Baseband ID: 9900

12:44:29| Protocol Version: 3.1

12:44:29| Warning: IMEI name does not match GDFS name (IMEI:NULL GDFS:W580)

12:44:29| ...using GDFS name

12:44:29|

12:44:29| Profiling SEMC phone...

12:44:29| Platform: DB2020

12:44:29| OTP CID: 51

12:44:29| EROM CID: 52

12:44:29| EROM Color: Red

12:44:29| IMEI:

12:44:29| Phone ID: W580

12:44:29| Region: EUROPE_1

12:44:29| CDA: CDA12345678/123 R2A

12:44:29| Firmware Version: R8BE001

12:44:29| EROM: R3A022

12:44:29| Ready for operation!

12:44:59| After making any changes with FSX

12:44:59| you must press the 'Shutdown' button

12:45:13|

12:45:13| Sending db2020_cid01_prodid_p3j.bin...

12:45:13| Applet ID: 070129 0950 NGUCXC1250330_DB2020_PRODUCTIONIDLOADER_P3J

12:45:13| This is a PRODUCTION_ID loader

12:45:13|

12:45:13| Sending db2020_mem_patcher_cid52_r2a006.bin...

12:45:14| Applet ID: 061205 1523 HANCXC9876543210_DB2020_MEM_PATCHER_R2A006 0

12:45:14| This is a MEM_PATCHER loader

12:45:14|

12:45:14| Sending db2020_cid52red_flash_r2a005.bin...

12:45:14| Applet ID: 061201 1314 HANCXC1329129_DB2020_FLASHLOADER_R2A005

12:45:14| This is a FLASH loader

12:45:14| Sendinging shutdown signal to phone...

12:45:14| Done.. You may now connect again...

12:45:14| Shutting down...