[T-Mobile Samsung Galaxy S II SGH-T989] sluchy523:
BACKGROUND:

At first, it just started turning off for no reason (probably a month and a half ago).

Then this week, it would start to randomly turn off, and start vibrating constantly when charging. After fiddling with the buttons, it would eventually find itself into download mode and then later turn itself on.

NOW:

Monday morning, after several days of draining the battery to 0% (due to me solely charging it for an hour a day), the phone went dead. Then, that night, upon trying to charge it and turn it on, it remained stuck on a black screen. After taking out the battery, it would continuously beep while still connected to the charger. As soon as I put in the battery, it would become COMPLETELY unresponsive, with and without the charger. After fiddling with it for over an hour, I put it down and slept, leaving the battery and charge in the phone.

Tuesday morning, I clicked the power button, and the phone flashed to the lock screen. It displayed it was at 0% battery, but I think it showed a charging sign. I used the phone for almost 2 minutes, checking my texts, before it again went completely black. The phone became completely unresponsive (no beeping or anything, regardless of anything I did). I connected it to a wall charger again, and left it there for the entire afternoon.

Then when I picked it up at around 6 o clock, I discovered that the continuous beeping stopped, and it would only beep after holding the power button for around 5 seconds. It could beep regardless of whether the battery was out or not.

After charging it all that night, I found I could make it flash the Samsung logo for a fraction of a second after holding down both volume buttons and the power button. I looked it up, and supposedly it brings you to recovery mode, but I believe my phone is switching off immediately after bringing up the logo.

At around 12, Tuesday night, I again decided to hold down the power button (just to reassure myself of it still somewhat functioning), and it powered on for around ten seconds (!!!) . It got all the way to the end of the pink loading bar screen, but then beeped and restarted. The second time, it lasted only around three seconds, without even getting to the loading bar screen, before powering off. It became completely unresponsive afterwards, no beeping, regardless of where it was charging and whether the battery was in or not.

Wednesday morning (today), after having left it charge all night, the phone still was completely unresponsive. I then left it to charge the entire afternoon (until now), and it was still completely unresponsive. I took it apart and played around with the power button, but it didn't seem to be stuck. I've now put it back together and leaving it connected to the wall charger once again.

What I've Tried:

Tried connecting it to Kies (computer doesn't even recognize it)

Tried putting into Recovery Mode (unresponsive)

Tried putting into Download Mode (unresponsive)

Switched chargers (unresponsive)

Held power button (beeps, now doesn't do anything)

Held both volume buttons and power button (beeps then quickly flashes samsung logo)

Cleaned off some of the micro usb lint with a tooth pick (coincided with the stopping of continuous beeping, not sure if it caused it)

What I think it could be:

Faulty power button (this is what I thought it was, but now it's not vibrating)

Faulty battery (I kept draining to 0%, but if this is the problem, it doesn't explain the phone not displaying anything when it's connected to a charger w/o battery inside)

Faulty usb charging port (I've heard it sometimes causes vibration problems. wouldnt explain the restarting).

Fried motherboard (phone has had some water damage, but I'm not sure if it's the MOBO, considering its symptoms)

HELP WOULD BE GREATLY APPRECIATED.