Google+ not support Android v4.1 or older versions anymore. Google Play Services collapse all the time and I cannot play any online games on my favourite device. ASUS do not support this model since 2015 August.
I tried to update Android in many way: with root apk (Kingo Root, iRoot, Towelroot, Kingroot, Oneclick root), no way!
ADB + Fastboot installed on my PC with USB driver successfully, tablet in developer mode with enabled USB debugging. I cannot find any TWRP image file for this model anywhere. When tablet in bootloader mode and I try unlock bootloader (fastboot oem unlock, fastboot flashing unlock) then I got “Unknown command” message. I cannot find any OEM unlock possibility in Developer options menu as well. Similar tablets TWRP images (TF300T, TF201, TF700T, Zenfone2) causes “Flash CMDS error” message always.