Pinephone not booting, always vibrating

[Blackheart]

My pinephone (postmarketOS edition) was on, and working normally when it immediately turned off. It can be that the battery is flat.

When plugging in the power, the red light turns on, and the phone immediately starts vibrating without stopping. Screen remains black.

Same behavior without battery.

What can I try to resolve the issue?

I just had this same thing happen to my pinephone pro, with tow-boot, manjaro on emmc, kali on sd
if i tried to boot manjaro it would appear to get about half way though the boot, then die, and restart, looping. 
if i hit the button to boot kali, it would appear to die almost immediately, then come back doing the solid red, soilid buzz. it would keep doing that until i both unplugged, and removed the battery.
What i found that worked was, after removing the battery and unplugging it, id put the battery in , then hold volume up as i plugged it in. the light would show blue, indicating its in usb storage mode, and it would just chill there charging. after a min, i tried again, and it boot normally.