As it's a new machine, I feel your remote has gone faulty. The bit that makes me suspicious is the turning it's self off. I had a new Sony VHS player where the very same thing happened, the input device had nothing to do with it, it was just a coincidence.
On the occasions the remote did work and switch the machine on, I hid it under a cushion, or the damn thing would turn it off again.
You may have another problem, but this seems most likely.