Touch screen not working after LCD+Ribbon replacement
I have replaced the screen of a Lenovo Tab M8 (8505) in full with a working LCD screen due to the original being damaged.
The LCD works to display image fine but the touch doesn't register at all.
At the same time I done two of these devices, with the exact same parts, one works, so I tried swapping the ribbon cables + LCD/Screen from the working into this device, and the working one remained working and the other remained touchless, still. This to me confirms that both the new screen and existing ribbon cables are fine (since they all work on that one device).
I'm not totally sure the next direction to look at for the device with touch issues regardless of LCD/Screen+Ribbon cable, at a guess motherboard issues? I had a bit of a look and there are no shorts or missing components easily visible from the front side, and I've also done a factory reset to try and rule out software issues.
Does anyone else have any idea? Many thanks