Black Screen after Replacement of LCD

Hello everyone. I recently met an issue with my iMac where the LCD got cracked and only a small portion of it would display correctly whereas the rest would look like a screen bleed.

I ordered a replacement screen from TaoBao China and it arrived. I followed iFixIt's guide on replacing the LCD screen and was done within an hour.

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Problem

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Upon booting, the iMac would show the Apple logo, booting into OS X. However, the screen stops displaying after the progress bar goes through the halfway mark.

Another funny thing, after the halfway mark, it would show the image onto the external screen.

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Troubleshooting Done

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- I have double checked all my wires and connectors, everything is fine.

- I have swapped out the brand new LCD and put in my old broken one to make sure the Mac was still functional, it still boots fine even the LCD is screwed up.

- Safe Boot, still the same symptoms.

- I even went to an Authorized Service Provider locally and for some reason, their diagnostic tool was able to keep the screen on during diagnostics.

They told me it was something logic board related issue but I don't believe their advice when the old busted up screen is able to boot up fully to the login screen.

- PRAM reset was rather tedious as it would completely disable the LCD screen, leading me to disassemble the iMac again and reactivate the screen driver by putting my old screen in and swapping out again for the replacement one.

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Suspicions

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LCD Incompatibility?

- I noticed the model numbers were different slightly different. The old busted one was LM215WF3 (SD)(C2), while the replacement one was LM215WF3 (SD)(B1).

Anyone got any better ideas? I'm getting a little tired, even Google or Apple couldn't help me out with this.