I can hear sound during start up but the display only works randomly. How do I fix it?

The screen on my 13" Mac book pro willl not work.

-When I turn the computer on I hear the start up sound.

-I see a faint display of the background when I shine a bright light on it.

-I tried brightening the screen and it did not work.

-I tried all system restarts and still does not work.

My mother picked up my computer the day after it stopped working at the screen randomly worked for about a week before the screen failed again. The same symptoms applied.

I took it to a shop to get fixed. When I went to pick the computer back up, he explained to me that he took the computer apart and before he touched any parts inside, the screen randomly came back on. He didn't charge me for it and he wasn't sure what caused it.

A week after I got my computer back the screen gave out and the same symptoms apply.

My guess is a loose connection. If you know what it might be can you please attach a way to fix the problem? I heard it might be the inverter cable but I don't know which cable that is or where it may be loose. Pictures or videos will be a great help.

There is NO WARRENTY left on the computer.