hawkeye

Hello, please help if you can. My S3 print head moves suddenly along X-axis or diagonally and drilling the edges even one minute after I turn it on. First time it happed during long print and after started to happed more often. First time It completely destroyed two AA cores installed. If I check stop switches I see reaction on the screen 4-8 seconds after I press it. Checked the mainboard and found that the mainboard partially covered in sticky transparent oil, most likely coming from thermal pad. The replacement costs around $1k but I'm not 100% sure that it's the mainboard issue. Please let me know if you have any ideas.