Holy ****!!! I think I may have found the fix! I have had the same exact problem as everyone in here. It seems to happen once I root. My Rezound would die completely, then after plugging it in, the light would come on for 5 seconds or less then shut off. I plugged it into my computer and Windows makes the USB Connected sound, so I figured something is happening.
I went into my command prompt and *adb devices*. It showed my device, but says in recovery mode. I then *adb reboot bootloader* and the bastard rebooted into bootloader! From there, I chose "REBOOT" and it fired right back up! Anyone who is having this problem, please try this and let me know if it works for you!
***UPDATE***
It appears when the battery dies all the way and then doesn't charge, the phone is automatically going into recovery mode even though nothing shows on the screen. I had my SIM card out when I tried this the first time, then when putting my SIM back in, it started doing the same thing. But again, it was going directly into recovery mode. This time, I tried a simple *adb reboot* and BAM! I'm back up and running! Again, let me know if this works for you, or if you need help doing this, let me know.