Computer shuts down after displaying the "Do you want to quit" alert

I got the alert "Do you want to shut down" alert without touching the quit button and the MBPRetina shut down immediately. After many attempts to fix the problem I took it to Apple service in Colombo, Sri Lanka and they quoted $1100 to replace the Keyboard.

I then restarted it with the Option key down and it worked normally for 18 hours and the Shut down alert appeared again and this time I was able to get the cursor to NO and stalled a shutdown.

There was no water damage at all and it is working again but I get the shut down warning after some time.

Is there a possibility of fixing this problem to avoid paying half the cost of a new computer?