STM32 SWD 下载失败

从网上买的POS机，处理器是 STM32F401CC，已引出SW接口，j-link识别，但下载失败。求大神指点 原谅，刚注册没有积分



附上错误信息
Build time Elapsed: 00:00:07
Load "D:\Keil工程源文件\ARM_STM32F401CCU6\Output\STM32F401CC.axf"
Set JLink Project File to "D:Keil工程源文件ARM_STM32F401CCU6JLinkSettings.ini"
* JLink Info: Device "STM32F401CC" selected.

JLink info:
------------
DLL: V4.96d, compiled Jan 29 2015 11:45:37
Firmware: J-Link ARM-OB STM32 compiled Aug 22 2012 19:52:04
Hardware: V7.00
S/N : 20090928
Feature(s) : RDI,FlashDL,FlashBP,JFlash,GDBFull

* JLink Info: Found SWD-DP with ID 0x2BA01477
* JLink Info: Found SWD-DP with ID 0x2BA01477
* JLink Info: Found Cortex-M4 r0p1, Little endian.
* JLink Info: FPUnit: 6 code (BP) slots and 2 literal slots
* JLink Info: TPIU fitted.
* JLink Info: ETM fitted.
ROMTableAddr = 0xE00FF003

Target info:
------------
Device: STM32F401CC
VTarget = 3.300V
State of Pins:
TCK: 0, TDI: 0, TDO: 1, TMS: 0, TRES: 1, TRST: 0
Hardware-Breakpoints: 6
Software-Breakpoints: 8192
Watchpoints: 4
JTAG speed: 4000 kHz

Erase Failed!
Error: Flash Download failed - "Cortex-M4"