When the moderator posts links to troubleshooting and there are no other solutions that can be offered, the moderator marks the issue solved (as the only solution is to follow the links, since each instance of the occurrence may have different causes), or the issue was solved for the original poster.
That you are having the issue a year later may be due to other issues with *your* particular device. You can certainly clear the cache, because one does that from the recovery partition, which one can only get to from startup. If you cannot turn your phone off because you cannot enter your credentials, you will have to either let the battery run down, recharge and follow the instructions below, or force restart it by holding the power and volume *down* buttons until the phone restarts, then tap the volume *up* button as soon as you see the Samsung logo on the screen, while letting go of the power button.
