On the R41Z Eval board, you can access maintenance mode by holding down reset while powering on. Power-cycling should revert the board back to debugging mode.
If power-cycling does not work, you'll need to re-program* the debugger firmware image with either J-Link's or P&E Micro's OpenSDA. The J-Link version is recommended.
*Once you have the correct bin file, simply drag it into the MAINTENANCE directory.
Finding the J-Link OpenSDA Image (factory default)
- Go to Segger's J-Link Downloads page: https://www.segger.com/downloads/jlink#JLinkOpenSDABoardSpecificFirmwares
- Expand the "J-Link OpenSDA - Board-Specific Firmwares" section.
- Click "Download" on the FRDM-KW41Z version
Finding the P&E Micro's OpenSDA Image
- Go to P&E Micro's OpenSDA support page: http://www.pemicro.com/opensda/
- Download the OpenSDA Firmware zip file.
- Use "DEBUG-FRDM-K22F_Pemicro_v108b_for_OpenSDA_v2.1.bin" from the zip file.