I had a similar issue as reported by toastee0 with openocd.
TargetName Type Endian TapName State
-- ------------------ ---------- ------ ------------------ ------------
0* nrf54l.cpu cortex_m little nrf54l.cpu unknown
1 nrf54l.aux mem_ap little nrf54l.cpu running
I was able to recover the board with a j-link edu. Claude the AI recommended this set of commands and it recovered the board.
# Launch J-Link Commander
JLinkExe -device nRF54L15_xxAA -if SWD -speed 4000
# In the J-Link prompt:
connect
halt
erase
loadfile firmware.hex
reset
go
exit
I have been avoiding that board so I can’t say if it is fixed for good.