Issue Flashing .hex File to nRF54L05 BLE Board Using J-Link Commander

Question

We are encountering an issue with flashing firmware to our newly designed nRF54L05 BLE board.

Issue Details:

We are trying to flash a .hex file (simple Blinky code to toggle an LED) using J-Link Commander with a J-Link Segger debugger.
The J-Link software identifies nRF54L15 but does not list nRF54L05 in the supported device list.
We proceeded by selecting nRF54L15 assuming compatibility, and flashed the Blinky code successfully (no flashing errors reported).
However, after flashing, the board shows no activity — the LED does not toggle, and the firmware seems to have no effect.

Below is J-Link Logs

SEGGER J-Link Commander V8.18 (Compiled Mar 5 2025 14:43:35)
DLL version V8.18, compiled Mar 5 2025 14:42:43

Connecting to J-Link via USB...O.K.
Firmware: J-Link Lite V9 compiled Feb 2 2021 16:32:48
Hardware version: V9.00
J-Link uptime (since boot): N/A (Not supported by this model)
S/N: 229003252
License(s): GDB
VTref=3.277V

Type "connect" to establish a target connection, '?' for help
J-Link>connect
Please specify device / core. <Default>: NRF54L15_M33
Type '?' for selection dialog
Device>?
Please specify target interface:
J) JTAG (Default)
S) SWD
T) cJTAG
TIF>S
Specify target interface speed [kHz]. <Default>: 4000 kHz
Speed>
Device "NRF54L15_M33" selected.

Connecting to target via SWD
ConfigTargetSettings() start
ConfigTargetSettings() end - Took 21us
InitTarget() start
InitTarget() end - Took 3.63ms
Found SW-DP with ID 0x6BA02477
DPIDR: 0x6BA02477
CoreSight SoC-400 or earlier
AP map detection skipped. Manually configured AP map found.
AP[0]: AHB-AP (IDR: Not set, ADDR: 0x00000000)
AP[1]: APB-AP (IDR: Not set, ADDR: 0x00000000)
AP[2]: MEM-AP (IDR: Not set, ADDR: 0x00000000)
Iterating through AP map to find AHB-AP to use
AP[0]: Core found
AP[0]: AHB-AP ROM base: 0xE00FE000
CPUID register: 0x411FD210. Implementer code: 0x41 (ARM)
Feature set: Mainline
Cache: No cache
Found Cortex-M33 r1p0, Little endian.
Cortex-M (ARMv8-M and later): The connected J-Link (S/N 229003252) uses an old firmware module that does not handle I/D-cache correctly. Proper debugging functionality cannot be guaranteed if cache is enabled
FPUnit: 8 code (BP) slots and 0 literal slots
Security extension: implemented
Secure debug: enabled
CoreSight components:
ROMTbl[0] @ E00FE000
[0][0]: E00FF000 CID B105100D PID 000BB4C9 ROM Table
ROMTbl[1] @ E00FF000
[1][0]: E000E000 CID B105900D PID 000BBD21 DEVARCH 47702A04 DEVTYPE 00 Cortex-M33
[1][1]: E0001000 CID B105900D PID 000BBD21 DEVARCH 47701A02 DEVTYPE 00 DWT
[1][2]: E0002000 CID B105900D PID 000BBD21 DEVARCH 47701A03 DEVTYPE 00 FPB
[1][3]: E0000000 CID B105900D PID 000BBD21 DEVARCH 47701A01 DEVTYPE 43 ITM
[1][5]: E0041000 CID B105900D PID 002BBD21 DEVARCH 47724A13 DEVTYPE 13 ETM
[0][1]: E0040000 CID B105900D PID 000BBD21 DEVARCH 00000000 DEVTYPE 11 TPIU
Memory zones:
Zone: "Default" Description: Default access mode
Cortex-M33 identified.
J-Link>loadfile merged.hex
'loadfile': Performing implicit reset & halt of MCU.
Reset type: NORMAL (https://wiki.segger.com/J-Link_Reset_Strategies)
Reset: ARMv8M core with Security Extension enabled detected. Switch to secure domain.
Reset: Halt core after reset via DEMCR.VC_CORERESET.
Reset: Reset device via AIRCR.SYSRESETREQ.
Downloading file [merged.hex]...
J-Link: Flash download: Bank 0 @ 0x00000000: 1 range affected (32768 bytes)
J-Link: Flash download: Total: 0.449s (Prepare: 0.110s, Compare: 0.000s, Erase: 0.061s, Program: 0.204s, Verify: 0.011s, Restore: 0.061s)
J-Link: Flash download: Program speed: 156 KB/s
O.K.
J-Link>loadfile merged104on.hex
'loadfile': Performing implicit reset & halt of MCU.
Reset type: NORMAL (https://wiki.segger.com/J-Link_Reset_Strategies)
Reset: ARMv8M core with Security Extension enabled detected. Switch to secure domain.
Reset: Halt core after reset via DEMCR.VC_CORERESET.
Reset: Reset device via AIRCR.SYSRESETREQ.
Downloading file [merged104on.hex]...
J-Link: Flash download: Bank 0 @ 0x00000000: 1 range affected (32768 bytes)
J-Link: Flash download: Total: 0.427s (Prepare: 0.105s, Compare: 0.000s, Erase: 0.040s, Program: 0.207s, Verify: 0.011s, Restore: 0.061s)
J-Link: Flash download: Program speed: 154 KB/s
O.K.
J-Link>r
Reset delay: 0 ms
Reset type: NORMAL (https://wiki.segger.com/J-Link_Reset_Strategies)
Reset: ARMv8M core with Security Extension enabled detected. Switch to secure domain.
Reset: Halt core after reset via DEMCR.VC_CORERESET.
Reset: Reset device via AIRCR.SYSRESETREQ.
J-Link>loadfile merge.hex
'loadfile': Performing implicit reset & halt of MCU.
Reset type: NORMAL (https://wiki.segger.com/J-Link_Reset_Strategies)
Reset: ARMv8M core with Security Extension enabled detected. Switch to secure domain.
Reset: Halt core after reset via DEMCR.VC_CORERESET.
Reset: Reset device via AIRCR.SYSRESETREQ.
Downloading file [merge.hex]...
J-Link: Flash download: Bank 0 @ 0x00000000: 1 range affected (110592 bytes)
J-Link: Flash download: Total: 1.103s (Prepare: 0.157s, Compare: 0.000s, Erase: 0.042s, Program: 0.774s, Verify: 0.031s, Restore: 0.098s)
J-Link: Flash download: Program speed: 139 KB/s
O.K.
J-Link>loadfile mergeObserver.hex
'loadfile': Performing implicit reset & halt of MCU.
Reset type: NORMAL (https://wiki.segger.com/J-Link_Reset_Strategies)
Reset: ARMv8M core with Security Extension enabled detected. Switch to secure domain.
Reset: Halt core after reset via DEMCR.VC_CORERESET.
Reset: Reset device via AIRCR.SYSRESETREQ.
Downloading file [mergeObserver.hex]...
J-Link: Flash download: Bank 0 @ 0x00000000: 1 range affected (114688 bytes)
J-Link: Flash download: Total: 1.164s (Prepare: 0.175s, Compare: 0.000s, Erase: 0.047s, Program: 0.802s, Verify: 0.034s, Restore: 0.104s)
J-Link: Flash download: Program speed: 140 KB/s
O.K.
J-Link>loadfile mergedNew.hex
'loadfile': Performing implicit reset & halt of MCU.
Reset type: NORMAL (https://wiki.segger.com/J-Link_Reset_Strategies)
Reset: ARMv8M core with Security Extension enabled detected. Switch to secure domain.
Reset: Halt core after reset via DEMCR.VC_CORERESET.
Reset: Reset device via AIRCR.SYSRESETREQ.
Downloading file [mergedNew.hex]...
J-Link: Flash download: Bank 0 @ 0x00000000: 1 range affected (114688 bytes)
J-Link: Flash download: Total: 1.210s (Prepare: 0.167s, Compare: 0.000s, Erase: 0.048s, Program: 0.855s, Verify: 0.034s, Restore: 0.104s)
J-Link: Flash download: Program speed: 131 KB/s
O.K.
J-Link>