The phone doesn’t need to boot to put it into serial download mode. The way to guarantee the phone gets to serial download mode.
- unplug phone and remove battery
- hold vol+ and re-insert battery
- while still holding vol+ plug in the USB cable connected to the laptop
run dmesg on the laptop and it should show that an NXP device has been connected.
You can always connect support@puri.sm for help with the reflashing procedure