There are a few steps you can take to try and troubleshoot the issue.
Firstly, as you have mentioned, a possible cause of the error could be a sticky key. If this is the case, you may be able to resolve the issue by cleaning the keypad or replacing any keys that are sticking.
If the error persists after checking for a sticky key, you may want to try resetting the HMI terminal. To do this, you will need to disconnect the power supply, wait a few minutes, and then reconnect the power supply. This will perform a cold start of the device and may clear the error.
If the error still persists after resetting the HMI terminal, you may need to consult the user manual
