TQ2440---Format the Nand Flash出错

TQ2440从nor flash启动后按9选择
[9] Format the Nand Flash

Really scrub this NAND flash? <y/N> : y
Erasing at 0x500000 --   2% complete.
NAND 256MiB 3,3V 8-bit: MTD Erase failure: -5
Erasing at 0x1980000 --  10% complete.
NAND 256MiB 3,3V 8-bit: MTD Erase failure: -5
Erasing at 0x3ae0000 --  23% complete.
NAND 256MiB 3,3V 8-bit: MTD Erase failure: -5
Erasing at 0xa140000 --  63% complete.
NAND 256MiB 3,3V 8-bit: MTD Erase failure: -5
Erasing at 0xc7a0000 --  78% complete.
NAND 256MiB 3,3V 8-bit: MTD Erase failure: -5
Erasing at 0xf320000 --  95% complete.
NAND 256MiB 3,3V 8-bit: MTD Erase failure: -5
Erasing at 0xfae0000 --  98% complete.
NAND 256MiB 3,3V 8-bit: MTD Erase failure: -5
Erasing at 0xffe0000 -- 100% complete.
OK
  MTD Erase failure: -5
这个错误是怎么回事？？？？