We have a bootloader for SAMD21J18A microcontroller with a custom board and pinout. We can upload a single program but the USB serial connection goes down and doesn't come back up. I can't access the bootloader through the Arduino IDE or the serial connection that should be available once my program is uploaded (simple hello world program). The power is fully removed between programming and attempting to open the serial port.
Is this a problem with the bootloader?