28335 串口烧录程序

*** PLEASE RESET TARGET IN SCI BOOT-LOADER MODE ***
Connecting with target (autobaud)...  OK.
Bootloading...  OK.
Connecting with target...
-Chip ID: 0xEF
-Chip Rev: 0x01
 OK.
Unlocking target...  failed (wrong key)!

怎么解决呢