It's the SM-T310. The not recognized happens if my USB cable isn't the one that came with the tablet or is inferior or broken in some way. It also pop up unrecognized as the tablet is booting so to me THAT IS NOTHING more than how things work today.
Since the recovery mode is borken I think you have to decide your next move. Mine would be accepting it's broekn and find a YouTube how to get to the battery to unplug that for a minute, plug it back in and try again.
Hello so my Samsung Galaxy Tab 2 will not start up anymore, going to the recovery mode with volume up + power does not work, holding power button does nothing, it is fully charged, tried two working cables. When plugging into PC it is not recognized at all, but if I hold the power button for about 10 seconds on tablet, PC starts saying and flashing a message "device not recognized" and shows up as an "unknown device" in Device Manager in Windows. But that is all I can do. Any idea what can help?