xbox error ( urgent !)

[Calazar]

A friend of mine ,gave me his xbox to put a chip and a dashboard. I moded it ,i put the dashboard ,i put some programs and games and it was ok .I saw him that it was ok before he took it . When my friend took it to his house and turn it on, an error messege apeared "Your xbox needs service, contact your dealer for suport " (something like that and it was flashing red and green ). Do you know what is this error about?

thank u