Is bootloader update failsafe?

[Travis Hendrickson]

I'm using:

• bootloader_secure example in SDK 12.3.0
• SoftDevice S130 nrf51 2.0.1

Is a bootloader update 100% failsafe against power loss anytime during the process?

[lance fisher]

There is one failure scenario that affects most self-bootloaders. If the image you are loading is not functional you will brick the device. For an extreme example if you created an image that simply halted the processor but is in all other ways valid the bootloader will happily replace itself with that garbage. This issue can be mitigated by ALWAYS verifying the operability of any new software images released to the field.