Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
I think that you might need to try holding down the Volume Down button instead, then pressing and holding the Power button. If you are looking for the sequence for a hard reset (which, be it noted, will wipe all your data off the phone!) that might be the right thing to do.
Do you need to reset the trouch-drag password ?
...it may seem odd for me to say this at this point, but: What maker and model is your tablet (or, you son's ... the 'subject tablet', that is) ? because I cannot figure out, now that I really think about it, what an 'E 4EB' tablet is.
With that information, I might be able to advise you further.