If you play often with android ROMs you have probably suffered a boot-loop. Sometimes it happens because you didn'd wipe well the caches. The standard boot loop reboots your device again and again to the splash screen of your phone or tab brand. However this time I have resolved quite a different boot loop. I can't really tell what was the cause of this problem, this was my brother's tablet. He just told me he had been playing with ROMs.
In this case it was a TWRP recovery loop. When I started Galaxy Tab 3 it was booting allways into TWRP. The tipical button combination (Volume Down + Home + Power) for download mode was not working.
I was reading a lot and watching some videos on Youtube. Some of them talked about a dd command that you could use through ADB access or direcly on the command shell of TWRP.
This command is the following:
dd if=/dev/zero of=/dev/block/platform/msm_sdcc.1/by-name/fota
But it didn't work for me as I didn't have that msm_sdcc.1 folder. I tried it on the file systems I had but nothing happend.
I just wanted to enter Download Mode to try to upload a Stock ROM I downloaded from samsung-updates.
As I was playing with TWRP menu I realised that there is a Download button on the Reboot menu. By pressing it I entered in Download Mode and using ODIN I could upload to my Tab3 the Stock ROM and now everything works like a charm.