Same problem different solution
First of all.. I have dropped my Moto G in the toilet.. 5 seconds later i was blowing water (clean thankfully ) out of every orifice i could find, simcard.. jack, paper towels everywhere and a kind of a wierd panic dance.
I tried to Off the device but the cycle of death (On->bootloader->Off) had begun, with no tools to get to the battery (thanks for the innovative way not to get near the battery Motorola) i just watched as the overheated battery was pulled into the abyss.
Long story short, i got to this thread.. after trying everything I saw here to no avail, got to a hardware store bought a 6$ worth of tools and hands trembling opened the patient up. and this is the exact sequence of actions taken.
-Disconnect the battery from the motherboard.
-Inserted a high amperage charger (5V-3A) (back cover and second back cover off)
-Success.. the 0% screen apeared.. the front faced led started to work (~30sec pulse)
-Unpluged the charger
-Connected back the battery to the motherboard.
-Inserted the charger back
Success..0% screen after a while the M screen (android signed) and then the 0% again (a sign it was charging OK)
After a while (pressed the On/Off button with a credit card no metal near the phone ) i saw the 1%.. after 25 minutes of letting it alone to charge pressed again the On/Off and it boothed into Android.. 12% charged..
After it charged to about 30% switched to a USB charge method for a much lower amp and it's still charging as I write this (34%)
So again thanking Moto for the difficult way to get to the battery, i will advise you to try my method also if everything else fails.
Get creative of have a (low priced) brick for a door stop.