If you are looking to flash a new ROM or some mod on your Samsung galaxy Tab E, model number SM-T377P / SM-T560NU, you will have to install TWRP on it. So what is TWRP? It is a custom recovery that opens gates for installing third party firmware. Just keep in mind that after installing TWRP on your Galaxy Tab E tablet, you will no longer be able to avail warranty on it.
For this, you will have to download ODIN on your windows computer. Mac/Linux are not supported. You can download ODIN from here.
* Enable Developer Mode on your phone and unlock the bootloader from the Settings, if not done already. * Download a recent .tar archive from the links above for your device. * Reboot into Download Mode [Press Power+Volume Down+Home]. * Flash the tar archive using ODIN by clicking AP and selecting the .tar file you just downloaded.
It should now reboot. That is it. You have successfully installed TWRP on your Samsung Galaxy Tab E android tablet. You can now install any third party ROM on it.