Picked up a Sega Genesis Model 2 with a 'VA 2.3 USA' board.

The problem at hand is a black screen on power on both composite and RGB (official Sega RGB cable).

Diagnosis so far:
- receives power upon power on, voltage regulator functioning ok
- caps looking good
- traces to cart slot fine, cart slot cleaned, cart slot solder joints reflowed on underside of board. Wiggling the cart in the cart slot does nothing
- mini din connector seemed fine but replaced for a new one

Seems its a common issue, any other ides on what to check?