Xbox Turns Off after one minute and dosen't show anything on the TV

My xbox worked perfectly but when my niece came to visit my house she forced a coin on the cd/dvd drive and i didn't notice so after that day i try playing a music cd and it didn't detect it and i tried with a game and it also didn't detect it so i search through the internet and i had to repair it myself and take out the coin and the console worked fine after that but then it just turn on for 1 minute then turn off, what do i do?