To help diagnose what is wrong there are a few common issues that can help pin point an issue.

Make sure to use a known working Mega Drive for these tests.

Monitor the green and red LEDs on the Mega CD and compare them below.

Working fully

• Green light (and sometimes red) on for split second, then off
• Green light and red lights back on and full boot

No / Bad Disc Drive or Ribbon

• Green light on for a split second, then off
• Green light back on and hangs at boot screen with no MEGA CD / SEGA CD logo

Bad interconnect block

• Black screen with no LEDs at all on Mega CD