R9A02G021 programmed once but now dead

I managed to program my FPB-R9A02G021 board exactly once when I got it out of the box - so I know the J-Link OB is working and the J-Link tools are working, and the USB cable is working. However, now when I try to connect with JFlash, I get an error (see [Log 1 below]). I saw there was another thread reporting the same error message, but there was no solution.

If I move J8 to Closed and power up the board, then tap Reset, which in theory will stop any of my code executing, connecting with J-Flash produces [Log 2] below.

I tried soldering jumpers to J5 and J6 (which came as bare plated through holes) and selecting the 2-3 position, but that didn't affect J-Flash (I wondered if maybe having the UART pins floating made it stop working).

I installed the Renesas Flash Programmer hoping that maybe UART Boot mode was working and I could use that to program the chip (J5 and J6 on 2-3, J8 closed). Noting the line in the manual that says it will not enter the UART Boot mode on Power-On Reset and only on Reset, I pressed Reset and tried the Renesas Flash Programmer. It asked me for an Authentication Code, offering all-FFs as a default. Accepting the default, or selecting "Auto Authentication" produces [Log 3].

The only sign of life is if I:

1. Unplug the USB
2. Set J8 to closed
3. Plug in the USB
4. Wait a few seconds
5. Remove jumper J8
6. I observe LED1 illuminates (which could be my code executing)

However, even in this state, JFlash does not work.

Is my board really dead? What else can I try? Can I RMA it?

[Log 1]:

Application log started
 - J-Flash V8.12 (J-Flash compiled Dec 18 2024 15:28:23)
 - JLinkARM.dll V8.12 (DLL compiled Dec 18 2024 15:27:57)
Reading flash device list [C:\Program Files\SEGGER\JLink_V812\ETC/JFlash/Flash.csv] ...
 - List of flash devices read successfully (451 Devices)
Reading MCU device list ...
 - List of MCU devices read successfully (11667 Devices)
Creating new project ...
 - New project created successfully
Connecting ...
 - Connecting via USB to probe/ programmer device 0
 - Probe/ Programmer firmware: J-Link OB-RA4M2 compiled Oct  9 2024 11:01:47
 - Probe/ Programmer S/N: 1085508066
 - Device "R9A02G021" selected.
 - Target interface speed: 4000 kHz (Fixed)
 - VTarget = 3.300V
 - ConfigTargetSettings() start
 - ConfigTargetSettings() end - Took 16us
 - TotalIRLen = 5, IRPrint = 0x05
 - JTAG chain detection found 1 devices:
 -  #0 Id: 0x00000001, IRLen: 05, Unknown device
 - Assuming RISC-V TAP with DTM setup
 - Debug architecture:
 -   RISC-V debug: 0.13
 -   AddrBits: 14
 -   DataBits: 32
 -   IdleClks: 4
 - Memory access:
 -   Via system bus: No
 -   Via ProgBuf: No (0 ProgBuf entries)
 -   Via abstract command (AAM): May be tried as last resort
 - DataBuf: 0 entries
 -   autoexec[0] implemented: No
 - Failed to temporarily halt core during identification
 - Attaching to core failed. Trying again with connect under reset (ndmreset-bit)
 - Memory access:
 - Detected: RV32 core
 - Temp. halting CPU for for feature detection...
 - CPU could not be halted
 - Connect failed. Resetting via Reset pin and trying again.
 - ConfigTargetSettings() start
 - ConfigTargetSettings() end - Took 10us
 - TotalIRLen = 5, IRPrint = 0x05
 - JTAG chain detection found 1 devices:
 -  #0 Id: 0x00000001, IRLen: 05, Unknown device
 - ERROR: Timeout while waiting for core to halt after reset and halt request
Specific core setup failed.
 - CPU could not be halted
 - OnDisconnectTarget() start
 - OnDisconnectTarget() end - Took 18us
 - ERROR: Failed to connect.
Could not establish a connection to target.
 - ERROR: Connect failed

[Log 2]:

Connecting ...
 - Connecting via USB to probe/ programmer device 0
 - Probe/ Programmer firmware: J-Link OB-RA4M2 compiled Oct  9 2024 11:01:47
 - Probe/ Programmer S/N: 1085508066
 - Device "R9A02G021" selected.
 - Target interface speed: 4000 kHz (Fixed)
 - VTarget = 3.300V
 - ConfigTargetSettings() start
 - ConfigTargetSettings() end - Took 7us
 - Could not measure total IR len. TDO is constant high.
 - Failed to identify target. Resetting via Reset pin and trying again.
 - ConfigTargetSettings() start
 - ConfigTargetSettings() end - Took 6us
 - TotalIRLen = ?, IRPrint = 0x..000000000000000000000000
 - Executing init sequence ...
  - ERROR: Could not perform target reset
 - ERROR: Failed to connect.
Could not perform custom init sequence.
 - ERROR: Connect failed

[Log 3]:

Connecting the tool
Tool : COM port (COM5), Interface : 2 wire UART
Connecting to the target device
Setting the target device

Disconnecting the tool
Error(E100000C): A serial programming connection is prohibited for this device. (Command: 30, Response: DC)
Operation failed.