Hello, you could install SPSDK if you wanted [Installation Guide — SPSDK documentation].
Push the bottom of ISP then put the cable USB to the PC.
blhost -p COMxx get-property 1

The first command is to check the communication.
blhost -p COMxx get-property 11
Response status = 0 (0x0) Success.
Response word 1 = 512 (0x200)
Max Packet Size = 512 B
Security State = UNSECURE
blhost -p COMxx flash-erase-all

Do a mass erase.
blhost -p COMxx write-memory 0 C:\root_example\Debug\led_blinky.bin

The flashing was done.
Remove the ISP jumper and reset your device.
Best regards,
Pavel