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STM32F407VG - write protection after power supply failure

Question asked by dembicki.pawel on Jun 12, 2013
Latest reply on Jun 12, 2013 by fm
After power supply failure the processor is locked for writing. I've tried many ways to solve this, but with no result.

Processor refuses programming. Every attempt to change "Option bytes" with st-link utility finishes with:

15:29:23 : Could not set Option bytes! 
                  Please reset the target and retry.

Processor communicate through JTAG, but it's impossible to change RDP in any way.

I've tried:
1. St-link utility (result above)
2. openocd + "stm32f2x unlock 0" - no error message but proc is still locked
3. openocd + mww, mdw commands with instructions from reference manual, but registry values aren't changed.

Registry  "Flash option control register (FLASH_OPTCR)" value is set to 0x0fffffec. 

What else can I do to unlock?