Bootloader freezed when NRF_FICR-CODEPAGESIZE was broken

Question

My custom board sometimes freezed on initialization process of bootloader (SDK11 dual_bank_ble_s130) when after long running and reconnect the power.
However the symptoms is not all boards but likely around 1 in 10 boards. 
 I was able to debug the bootloader steps by the following way.
 devzone.nordicsemi.com/.../ 
 And I found that the NRF_FICR->CODEPAGESIZE was invalid value ( 0xF6F58FFB ). (it's supposed to be 0x00000400 ) 
 main.c (bootloader) 
 leds_init();

// This check ensures that the defined fields in the bootloader corresponds with actual
// setting in the chip.
APP_ERROR_CHECK_BOOL(*((uint32_t *)NRF_UICR_BOOT_START_ADDRESS) == BOOTLOADER_REGION_START);
APP_ERROR_CHECK_BOOL(NRF_FICR->CODEPAGESIZE == CODE_PAGE_SIZE);
 
 Therefore, my questions are: 
 
 Are there any possibility to
update NRF_FICR->CODEPAGESIZE value
in any functionality? 
 How can I
recover this value
(NRF_FICR->CODEPAGESIZE)? because
in spite of I erased flash and
re-flashed all again, I could not
start the program if it becomes so. 
 
 Any advice and suggestions will be greatly appreciated. 
 
 Best regards,

Bootloader freezed when NRF_FICR->CODEPAGESIZE was broken