New T68 Lynx update

There is a new update on the onyx-boox site for the T68 Lynx. You can also access it through settings on the device itself. I have tried downloading it from my device, and downloading it from the website and then transferring it to my device. Each time, the Lynx recognizes the update and begins the installation process. However, when the device reboots into recovery, I get this: E: signature verification failed. Installation aborted.

I have emailed Arta Tech for help on this.

Has anyone managed to successfully install the update? Are there any workarounds that might help in my case? And, last but not least, what improvements have you seen in the update?

Thanks!