Yeah true enough, the seller may not have plugged the A/V cable in, but it seems abit good to be true.
The TSOP can become temprimental sometimes and have a somewhat corrupt flash, meaning sometimes, especially from cold it'll boot, but if you power it on and off a few times, it may refuse to boot again for quite some time, if you leave it unplugged a couple of hours it'd probably boot again.
In some rare cases, ive seen the eeprom do this too, but this causes red flashing only.
Corrupt TSOP can sometimes result in a frag, sometimes a reflash can cure it, or the TSOP itself may be on its way out and would require a careful job of replacement.
I'd recommend once youve had it on for a while, you try and power cycle it a few times and see how you get on with it.
I guess other components could possibly cause some issues, but its not very common.
A real odd one i had yesterday, a motherboard would start up, you could hear sound, good green light, but nothing on screen.
At this point the majority would have said it was a deffinate eeprom issue, wrong it turned out to be a faulty RAM chip, i replaced it and its been working spot on so far, so it just goes to show how different components can have different effects.