First one I noticed is you should be pressing and holding power + volume down. You're saying volume +, but it should be volume -
To explain, after the complete battery drain when you are ready to power the tab on you should be holding power and the button directly next to it which is the volume - button. If you do this and are lucky enough to see anything at all release the power button but continue to hold the volume down button and hope. If you get the two icons you're getting even closer.
If you're sure you are pressing and releasing the buttons correctly, please excuse my ignorance and accept my apology for uselessly posting.
Best of luck wishes in any case.
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