Replacement LCD screen flickers

Hi

I have a nearly new Motorola Moto G 3rd Generation that I dropped and smashed the screen. It was fully functioning, but the front glass was shattered.

I bought a replacement screen / LCD / digitizer assembly from eBay and installed it. Initially, the screen appeared OK, but then started flickering at about 2 - 3 Hz. The screen appeared dull, but that is probably due to the flickering. It now consistently flickers, though is OK for a second or so on power up.

I performed a factory reset, but that didn't fix it.

I contacted the seller, who recommended I clean the contacts and try to seat the screen cable again. I've tried this a few times but it hasn't improved things.

Is this a defective screen? Note: I didn't disconnect the battery before replacing, because you can't get to the battery.

Many thanks

Mooncat