Originally Posted by ibub
I didn't mean black screen in recovery. I meant for you to try dd command from where you are bootlooping. Don't reboot recovery until you have used dd command to write the twrp recovery to recovery partition.
Ah, I understand now. I just tried and no dice, "cannot open for read: Permission denied"
It seems that I can finally say there is no hope for this thing. My issue is that I didn't allow permission to Shell in SuperSU, simple as that.
There is nothing that I can do because I can't access root permission to shell without being able to boot up. I can't uninstall SuperSU because it is a system app (and because it seems this phone is pretty borked, trying to install an app flashes errors in ADB).
Oh well, at least I have some replacement parts. Thanks everybody for all the help.