iMac screen is black

I just replaced my power supply on my iMac 21.5" EMC 2308.

Now when I turn on the power I just get the startup tune but the screen is black (partially lit) nothing else.

Desperate to have this fixed. Thank you.

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Can you explain why you replaced the power supply and is the system reacting differently now.

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Have your checked if your screen is connected to the power supply?

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What are the diagnostic LEDs telling you?

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