My LG LEON battery dead?

I was charging my LG LEON and it suddenly turned off with a 0 percentage of battery, then when i tried connecting it to the charger it didn't wanna charge. I tried with five different chargers and plugs but it still doesn't wanna charge. My company is T-Mobile, i called and they told me to take the battery out for 10-15 seconds and to put it on again to see what happens, but it did not work. What should i do?