[Nexus 7 (2013) Q&A] sfhub:
The build quality is inconsistent, even not accounting for the multi-touch.

For the multi-touch issue, though, I will guess it is voltage related.

For the current unit I'm testing, I've noticed that when fully charged there really aren't any noticeable multi-touch issues in regular usage. When the battery gets lower, I start noticing dead spots and occasional multi-touch issues.

I know from past experience if you start varying voltage things can behave very funny and inconsistent. Electronics are designed to operate with certain voltage ranges and once you go outside those ranges, the variance in their performance can be quite high.

I have a couple of Tivo's which had bulging capacitors in the power supply. One unit would boot loop all the time. One unit would flicker the svideo and component outputs. A 3rd unit could not initialize the 2nd CableCARD (leading to recordings that were cut short, only for shows assigned to the 2nd tuner). Now if it came out of the factory with the bad power supplies, based on the end results I could say the range of issues is great and the build quality is poor, but in reality the core issue was just one, and the range of behaviors I was seeing was just the expected variance to the out-of-spec voltage.

I had a slingbox with a voltage regulator going bad. For the first few months, the network was real choppy (which coincidentally happened right after a firmware upgrade). Next it stopped working with a gigabit switch, but if I plugged it into a 100mbit hub it would work. Then I got an error message in the player software that this unit wasn't made in the US. Eventually the unit just wouldn't boot. This was all the reaction to the voltage regulator failing and dropping voltage from 3.3v to 1.8v over time.

BTW all these problems were fixed with under $5 in parts to replace the failing caps and voltage regulators.

The reason I keep looking at voltage is because the way these capacitative screens work, they have a transparent metallic conductive coating and a voltage field is generated over the conductive layer. When your finger touches it draws a small amount of current causing a voltage drop, which is then detected and translated into a position by analyzing the current flow from each corner. The fact that this problem happens when you cross the lines (ie your fingers line up) means the voltage is dropping even lower on that axis since more current is being drawn.

People keep saying this is a grounding issue, but what is there to ground? It isn't like this is designed to attach to a 3-prong plug all the time with true ground. It runs on batteries. I am sure it is connected to the internal ground plane (relative to battery terminal) or things would work even worse. I am not a EE so maybe I just don't understand how it is supposed to work or what people are referring to with the grounding issue.

Anyway, my guess is someone attempted to lower the voltage to tweak some battery life out of this thing and that is causing some of the issues or maybe even a wide range of issues.

Multi-touch, random reboots, GPS system dropping out, screen flicker, corrupted /system causing OTA install to fail, units stuck on X could all THEORETICALLY be explained by voltage issues. Of course they could be something unrelated as well.