Headunit issue-ish

[MarkTeamF1]

Just bought a new unit to replace my faulty old one. Old one powered up, but no display on screen. Took it out, waited for my new one to turn up... it arrived, I plugged it into the ISO conversion block provided, turn car elec on and nothing, tried holding the power on on the headunit, still nothing... strange, so dug out the old headunit, and that won't power on either... any clues? I'm completely stumped!

 

[LOCKE]

Fuse?

 

[MarkTeamF1]

I shall check this. Any telltale signs it's blown?

I don't understand why it'd of blown if there hasn't been any need for power draw for a bit

 

[MarkTeamF1]

Sorted. No idea what it was, replaced the fuse anyway

 

[Gus]

Just bought a new unit to replace my faulty old one. Old one powered up, but no display on screen. Took it out, waited for my new one to turn up... it arrived, I plugged it into the ISO conversion block provided, turn car elec on and nothing, tried holding the power on on the headunit, still nothing... strange, so dug out the old headunit, and that won't power on either... any clues? I'm completely stumped!

Turn the car on - start the engine.
edit - too late