$ mozilla-apk-cli package.zip myapp.apk
To install myapp.apk, use adb and do
adb install myapp.apk
To re-launch your app from adb do
adb shell
# am start -a android.intent.action.MAIN -n com.firefox.cli.apk.packagedozten.p3ea7a6153641373b9751d2e48430c43f/org.mozilla.android.synthapk.LauncherActivity
Two pieces of information would be really helpful