From @ beginnerbigger
If you have J-link edu, you can reload the bootloader.
The process is documented here
http://djynet.net/?p=969
This link was found in this blog reference from Adafruit
https://blog.adafruit.com/2019/11/03/how-to-burn-bootloader-arduino-nano-33-ble-arduino-arduino/
Another reference using a different CMSIS-DAP Compliant SWD Debugger tool.
https://forum.arduino.cc/t/burn-bootloader-on-nano-33-ble-with-another-arduino/853922/6