Lockscreen is missing, can I reinstall the lockscreen somehow?
Now that you have USB debugging enabled, you can try resetting some of the database flags associated with the lockscreen...

You will have to adb push sqlite3 to your device, the only independent binary that worked for my devices I pulled from here: XDA - sqlite3 binary June 2015

adb shell
cd /data/data/com.android.providers.setting­s/databases
sqlite3 settings.db
update system set value=0 where name='lock_pattern_autolock';
update system set value=0 where name='lockscreen.lockedoutpermanentl­y';
.quit


If you happened to accidentally delete Keyguard.apk and the above does not work, you will have to get another Acer Liquid E3 off ebay or the like (about $80, all we need is the apk, then resell) and adb pull from the source phone and adb push to the destination phone.

I would recommend just flashing stock firmware, or pulling the apk's from stock firmware, but unfortunately that does not exist.