Diagnosis
The E1 error is a room temperature sensor fault. The unit's brain can't read how hot the room is, so it refuses to start.
How to Fix It
Unplug the unit for 10 minutes. This is a hard reset that often clears a temporary sensor glitch. Plug it back in. If E1 is gone, you're set. If E1 returns, the sensor inside the unit is likely faulty and needs professional repair.
If That Didn't Work
Check for any obvious physical damage to the unit or its cord that might be causing internal electrical issues. A damaged power supply can cause erratic sensor readings.
Heads Up
Don't try to open the unit and find the sensor yourself. The refrigerant system is sealed and requires a licensed technician to service.