I have Galaxy Tab 3 10.1 GT-P5210. I forgot the lock screen password, so I tried to hard reset the device using the recovery menu. (Power button + Volume up).
When I tried to hard reset, I got a lot of errors. I don't remember all of them, but I know that one of them was
E:format_volume: make_extf4fs failed on /dev/block/mmcblk0p9, and other error was
E: failed to mount /cache (Invalid argument).
The other errors were similar.
I tried again, and the same result.
I tried the option of 'wipe cache partition', and I got similar errors. (Or the same.. I'm not sure)
After that, I decided to try to get into the recovery menu again. So I pressed the reboot option, and I was pressing the volume up with the power button while it was rebooting.
And then, nothing happened. The device didn't power on again. I tried to charge it, with no success. I also tried to do a soft reset (Power + Volume down), and nothing happened.
There is something to do?