On 28-Dec-2024 I noticed the power tailgate stopped working on my 2021 Honda Odyssey. I tried to press the power tailgate button on the key fob, the button on the driver’s side control panel, and the button on the tailgate itself, but none of them works. I did some research online and found out it’s a common problem in 2018 to 2021 models and the cause was the failed Power Tailgate Control Unit due to water leakage through the cracks on the vehicle body. I opened mine and found there was water in the control unit box which might have caused short on the circuit board. I bought a new control unit a week later and it fixed the issue.