@Everybody with the exact problem described by the author...
Do you guys have your bootloader unlocked, like with "fastboot oem unlock"?
Well, I do. And I just locked it back ("fastboot oem lock" ) and I think my phone is actually coming back on, it's currently on the "Android is starting" screen optimizing app 12 of 151.
I'm just hoping the lock command doesn't reset my device like the unlock command obviously does... I guess I'll edit this with my results in like an hour when this is done (not literally an hour)!
EDIT 1: 10 minutes later, it seems to be stuck on "Starting apps." after it finished optimizing.
EDIT 2: 10 more minutes later, I'm pretty sure it was indeed frozen on "Starting apps.", so I took the battery out. I turned it back on only to see it still freezing on the Metro PCS screen... Well damn.
EDIT 3: Yet another 10 minutes later, still stuck on the Metro PCS screen...