Hi @ayaya
Check if any buttons are stuck down.
If not you will have to open the remote and clean the motherboard using Isopropyl Alcohol 99%+ (available from electronics parts stores) as something is shorting out the tracks on the board that the buttons make contact with when pressed.
Here's a [https://www.youtube.com/watch?v=8lNe3YiD9eU|video] that in principle shows what to do.