I have a Samsung Galaxy Avant with T-Mobile, showing down Android with "No command"

[AC Question]

I spent the day gardening, phone in my back pocket. At the end of the day, I find my phone is frozen on a picture of a green android with an open chest and a red triangle with an exclamation point. Below it says "No command." and some stuff that I've got no clue about. (#MANUAL MODE # / --Appling Multi-CSC...
Applied the CSC-code : TMB
Successfully applied multi-CSC.

Now send the package you want to apply to the device with "adb sideload <flilename>".

I've tried pressing the power button, but can't shut the phone down, and I can't get rid of this screen by pressing the home button. The android looks dead. Have I killed him?

 

[B. Diddy]

Welcome to Android Central! It's ok to pull the battery to force a shutdown. Wait 10 seconds, then reinsert the battery and power on normally. Does it work now?