A500 freezes

My Iconia A500 tablet had problem suddenly and it went frozen, can't be booted, can't go into recovery. Try to go into APX mode and flash it using babsector and V8-UNL-ICS-HC-bootloader-MULTI-cwm, neither works.

An example of the error message is as follows:

**********************************************************
* Press any key when your A500 is in bootloader mode *
**********************************************************
Press any key to continue . . .
Flashing HC-Bootloader...
Nvflash started
[resume mode]
Formatting partition 4 please wait.. Command Execution failed cmd 13, error 0x12
0002
FAILED!
command failure: format partition failed (bad command)
bootloader status: unknown operation (code: 1) message: flags: 0