Seeeduino LoRaWAN usb not recognised

After some program, I start to try the “wake up RTC interrupt” program to make the power consumption lower. But during this, the board starts not recognised by the computer. At first, it sometimes takes a lot of time to load a new program, later it just not recognised.

I might be powered off the board during loading new program, cause I’m not patient to wait. So, is that mean my bootloader is broken and need fix that? If so how to fix it, is it the same as Arduino?