NRF52 bricked with CONFIG_GPIO_AS_PINRESET and P0.21 tied to ground?

Try the  --eraseall or --recover options for nrfjprog.exe - it looks to me like reset is not connected when UICR is fully erased.

Hi,

Thanks for the quick answer. Unfortunately all IC related nrfjprog switches return "Segmentation fault: 11"

I found a post about a similar issue, though the author there did not explain how he solved the issue:
https://devzone.nordicsemi.com/f/nordic-q-a/51089/nrfjprog-10-3-0-segfault

I suspect he was able to disconnect P0.21 from ground and that's how he solved it. You of course don't have that option. 

The only thing I can think of you might try is using the CTRL-AP port to reset and erase the entire chip and UICR. That's what --eraseall does however I think perhaps the code there doesn't like the actual chip being in reset. If you read this thread https://devzone.nordicsemi.com/f/nordic-q-a/12484/approtect-and-dap you'll find the commands for using JLink to directly access the CTRL-AP port without attempting any real connection, it just sends simple SWD commands directly. No iterating access points or anything. 

If that doesn't work, I think you're bricked. It is not unlikely that reset is a very global signal which holds everything in the entire chip in reset until deasserted, that may well include the CTRL-AP port, unless someone cleverly thought about this kind of issue. You might want to try the above process several times just incase reset clears after a number of cycles on SWD on the AP. 

RK said:

If that doesn't work, I think you're bricked. It is not unlikely that reset is a very global signal which holds everything in the entire chip in reset until deasserted

I'm afraid this is true, it's a global HW reset state where CPU and HW state machines are halted.

The only way to un-brick your device is to sever your reset pin's connection to ground. 

Trying to use the CTRL-AP port seemed promising but you are right. The only way to get the board the work again, was to disconnect the reset pin from ground.