After I completely drained the battery, I was unable to charge the phone without pausing the boot during yellow screen and let it charge otherwise it would just reboot on start.
After force shutdown (holding for >1minute every time), I would be able to successfully unlock but it would again shutdown after unlocking, even tho battery was >50%. I was able to actually use the phone after doing this for several times.
I love GrapheneOS but I swear these obscure bugs never gets the attention for some reason.