Sometimes when replacing CD units, the stock ones bought from China or Hong Kong will not be configured correctly, either due to age or rough handling during shipping.
I know this can happen with, say, the Mega CD. Not 100% sure if this also applies to the Neo CD.
If someone on here has a copy of the Neo Geo CD Maintenance Manual, it would say for sure.
Usually, configuring a new laser for your CD based unit requires an oscilloscope so you can measure the frequency of certain test points and adjust the potentiometers on the unit until it matches the wave shape shown in the manual.
From what I remember though, the NGCD only has a laser power adjustment pot.
You could try taking a picture of its position, marking a notch on it, and turning it VERY VERY slightly (like, 1/32nd of a turn) and see if that helps make it read discs.
I'm not too familiar with the NGCD, so this is mostly based on my experience with Mega CD and TG16 CD lasers.