Hi
Please observe the waveform of Reset_b with an oscilloscope. Make sure it high.( not sawtooth wave)
Please confirm the PTA4(NMI_b) is high. If the NMI input is low and the NMI function is enabled in the NMI_DIS field(by default), this results in an NMI interrupt.
The RESET_b pin, if enabled, must have a 100 nF capacitor close to the MCU for transient protection. The NMI_b pin, if enabled, must not have any capacitance connected to it. Each pin, when enabled as their default function, has a weak internal pullup, but an external 4.7 kΩ to 10 kΩ pullup is recommended. As with power pin filtering, it is recommended to minimize the ground loop for the capacitor and the VDD loop for the pullup resistor for these pins.
The JTAG_TMS signal on PTA3 requires a strong pullup resistor for mode selection. For the debug interface, you can refer below image:

Do not connect 25MHz quartz crystal unit to RTC oscillator(XTAL32 and EXTAL32).
Best Regards,
Robin