The Xteink X4 and X3 are excellent alternatives to Kindles and Kobos if you want an e-reader that’s as easy to slip into your pocket – just not out of the box. Both devices come with stock firmware that’s clunky, limited, and occasionally confusing, but that can be easily fixed by plugging them into a PC to install alternative software called CrossPoint Reader which delivers a more polished user interface and improved functionality. But now buyers report Xteink is blocking the upgrade, which might depend on where you live and where you purchase its devices. The issue was first reported by a Reddit user earlier this week when they discovered the second Xteink X4 they had purchased from Taobao (a Chinese online retailer owned by Alibaba) wasn’t recognized as a USB device by their computer. After confirming their USB-C cable still worked with their original X4, the Reddit user contacted Taobao’s customer service.…