How to Diagnose/Treat Black Screen of Death(?)

[AC Question]

Hey all,

I ran into a problem on my walk home, wherein my phone (a Galaxy S4) decided to suddenly cut to black (as in, the screen is inactive, not that it's lit and displaying black) with 25% battery remaining while running Pokemon Go in the foreground. I assumed it was a weird power failure (my phone has died previously when I tried to start Pokemon Go at 11% battery), but it seems to be something more troublesome. Here's a rough summary of things I've attempted, and what that got me.

Removing & replacing (putting back in, not using a new battery) the battery, no charger cord: Phone starts to boot, but the screen cuts to black shortly after displaying "Galaxy S4."
Removing & replacing both the battery and the SIM card: Same as removing & replacing the battery.
Removing & putting the battery back in, with charger cord: Phone is unresponsive.
Removing & putting the battery back in, plugging the charging cord in immediately after the battery is replaced: Screen cuts to black shortly after displaying "Galaxy S4."
Pressing & holding the power button: No response.
Attempting to boot to recovery mode by pressing the requisite buttons while removing & replacing the battery: Same as removing & replacing the battery, but with the addition of "Recovery booting..." in blue in the upper-left hand corner appearing briefly after "Galaxy S4" is displayed (the screen continues to cut to black).
Connecting the phone to my computer: phone is undetected by Windows 7, confirmed by using the "adb devices" command from the Android SDK (list of attached devices is blank).

At this point I'm assuming my phone has become a brick, and I've mostly consigned myself to losing my progress in the couple of games I have installed. Is there a way to recover my contacts, though (e.g. some magical tool hiding in the AT&T store that can work on a brick)? Or is that lost to the digital aether as well?

Thanks in advance,
--Inumo

 

[jeffhaskins]

Can you go into download mode by holding vol- and power? If so you should be able to fix it with Odin and firmware from sammobile.com

 

[Inumo]

Hey jeffhaskins, OP here. When I try to go directly into download mode from my phone's current state, there's no response. When I remove & replace the battery while holding vol- and power, the warning for entering download mode comes on briefly before the screen cuts to black, with about the same timing as if I started the phone normally or attempted a recovery boot. If I act fast enough I can hit vol+ in time to confirm entering download mode, which seems to work properly (i.e. the screen displays the Android mascot with the word "Downloading..." underneath), but the screen still cuts to black shortly after.

As a side note, I tried charging my phone overnight, and it's still having this issue. I don't know enough about Androids to know if this is a hardware or software problem, but I don't think that it'd be worth it to try and drain the battery somehow and experiment from there. If anyone has a different opinion, feel free to share.