From my experience I understand what Jesus said in Mathew 6:6 (“when thou prayest, enter into thine inner chamber, and having shut thy door”) as going into our own INNER self and shutting the door so that no other thoughts come between you and your Father, and in this extremely PRIVATE setting, whatever your ask “Father will grant you.””
You're making a point with Mt 6:6 that the context doesn't support. The context shows that Jesus was simply instructing his followers to not pray out in public just to be seen by men - for show. He wasn't referring to being in private so one could clear thoughts, meditate, etc.
Mt 6:5,6 - 5"When you pray, you are not to be like the hypocrites; for they love to stand and pray in the synagogues and on the street corners so that they may be seen by men. Truly I say to you, they have their reward in full. 6 "But you, when you pray, go into your inner room, close your door and pray to your Father who is in secret, and your Father who sees what is done in secret will reward you.
Secondly, I've tried what you refer to for years and never received so much as a peep for an answer. In my work travels, I have pulled over late at night, walked out alone into open fields under starry skies and implored God to hear me and answer me - not asking for selfish things, but telling him I would do what he wanted if he would make what he wanted clear to me. After years, still no answer, unless his answer is to show me that JWs are wrong.
Thirdly, I agree with what some others have said about the proper "log on" procedure. Is an almighty, all-loving God so petty that he won't answer if one doesn't use the precise "log on" protocol? The Bible doesn't support what you say; it has accounts of people praying under all kinds of different circumstances.