5. Just to be clear, a press-and-hold of volume-DOWN and end/power simultaneously still results in a boot-loop? It doesn't stop and prompt for anything?
tried recovery mode still loops or w/e
The bootloader is different than recovery. If you can get into the bootloader, it will check for updates on the sd card and we can flash an update (2.1 rooted image) or something else (2.1 leak, maybe?) which could potentially clear up any software issues.
Edit:
MEGAUPLOAD - The leading online storage and file delivery service
Put this file on your sd card. Make sure the sd card is formatted to fat32, do not extract the file, do not rename it, and do not put it in any folders. After you do that, turn the phone off, and hold Volume Down and Power to turn it on. The boot loader screen should pop up with four options like fastboot, recovery, clear storage, and sim lock for a second and then should say
SD CHECKING
Loading <filename>.ZIP....
NO IMAGE!
SD CHECKING
Loading <filename2>.ZIP....
NO IMAGE!
...
Loading PB00IMG.ZIP...
(Edit 2: It will look something like this)
It will flash to a new screen where it will start verifying the file and then ask you if you wish to update. Say yes. It'll do some magic, and reboot into the bootloader again. It'll do pretty much the same steps again, but install some different stuff this time around. Hopefully, it'll boot after that.
This will install a new bootloader (1.49 S-OFF) and a rooted version of 2.1.