The error means that the debugger failed to connect to the target CPU. This can be for different reasons.
When troubleshooting the initial debug connection to the target CPU, it is recommended to use the CPU Reset instead of Download.
Try to confirm this with another working BlueBox system. In case you confirm that the BlueBox hardware is damaged, contact iSYSTEM support.
If pins in connectors (in most cases pin 40 on ST1 connector) are bent, possible errors are: Error 250: FP5 Serial Communication error (Renesas RH850), DAP initialization failed (Infineon TriCore), CPU initialization failed (NXP/ST Power Architecture).
Try to test the BlueBox on another target or try to replace the CPU with a new one.
Disable all reset sources during debugging. See further explanation.
Open Hardware / CPU Options / JTAG and configure the Scan speed.
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