Laptop shuts down automatically

Hello,



My laptop is acer aspire 5742g. Purchased years ago.But the problem is it shutdown automatically when using.
I gave it on the Repair shop. They told me that there was a board shot and they did repair. Then again the problem came again. I gave them back. They told me the probleme is one parts is damaged on the  board. we tried to fix the parts. But the parts is heating  and fall down
what i do tell me..