try touch the cable softly (the one between the 2 sockets) , might be a loose connection there.. anyway what i used to do was...
powered the machine up and showed early boot menu (hold both mousebuttons on reboot)
and when i was sure the screen was up, i used my amazing skills
and touched the cable until i got a picture, it worked indeed...later on i fixed the wire ofcourse but atleast i found out what was broken
...
