ARRIA II GX125 Dev Kit JTAG problem (UNKNOWN ID)

Hi Sir,
We are using a Arria II GX 125 dev board from ALTERA. it work well before. But now , it failed in JTAG download. In the Auto detect in programmer, a device named UNKNOWN_C0829037 will be detected. The screen shot is attached. Could anyone help me ? Thanks alot.

Attached Images

• JTAG UNKNOWN_ID.jpg (123.4 KB)