Horn Assembly problems of the 2016 Honda Odyssey

One day after changing engine oil at Honda dealershop last week Monday, there was flickering on dash board after turning the power off. The symptom was getting worse and on Sunday and Monday (yesterday), the car horn honking itself. And yesterday, the dash board power couldn't be turned off when I turned the power switch off (engine off luckily) and the flickering got worse last night. So, I did unplug the battery with a worry of fully drained battery overnight. Today morning, I plug the battery back and get the same issue, and luckily ignite the engine and went to dealer shop again. They did diagnosis and said keyless access control unit needs to be replaced. Here is the summary of the symptoms: last week flickering dash board with fcw system failed. And honking itself with keeping flickering. Yesterday, I saw error message of "keyless system error". And I went to dealershop in this morning. Here is my speculation: during oil change, there was oil spilling, which causes shorting of circuitry (or technician accidently hit some parts inside). It causes frequent on/off of electronic system, ending up breaking the keyless access control unit. The dealer didn't say anything, but charged me to replace the parts since my car is out of warranty.