I am sorry to hear the device is not turning on. One thing we can try is to try another battery to see if that fixes the issue.
inspect the phone for signs of physical damage and follow the device common procedure for checking the phone’s Liquid Damage Indicator (LDI).
Plug in the wall charger to a known working outlet and attach the device to the charger. The customer should verify the outlet is working by plugging another electronic device into it.
Note: It can take up to 20 minutes for a charging indication if the battery is completely depleted.
I would also follow up with our customer service http://support.t-mobile.com/community/chat
Thanks for posting