Diagnosis
This is typically caused by a wake-up signal from a connected device via HDMI-CEC, or a scheduled update/event from the Google TV system.
How to Fix It
First, disable the main culprit: HDMI-CEC (called Simplink on TCL). 1) On the TV, go to Settings > Channels & Inputs > Inputs. 2) Select "HDMI CEC" and turn it OFF. This stops devices like a cable box or game console from waking the TV. Next, check for automatic updates. 3) Go to Settings > System > Power & Energy. Look for "Power on by mobile app" or "Wake on LAN" and turn those OFF. Also, disable "Fast TV Start" if you see it.
If That Didn't Work
Unplug all HDMI devices from the TV. If the behavior stops, you've found the guilty device. Plug them back in one by one over a few nights to identify it, then manage that device's own power settings.
Heads Up
Google TV can also turn on for scheduled content recordings or reminders if you've set them up in the Google TV app. Check the "Settings > Accounts & Sign In > Your services" area for any linked services with scheduled events.