Sennheiser HD 450bt Malfunction?

My headphones seem to be malfunctioning or something? I didn’t get them long ago. I used them this morning and it was fine but when I went to turn them back on it is refusing to pair. Just says power on and flashes a couple times then remains blue. And then I cannot power it back off and none of the buttons seem to work and the refresh isn’t working. When plugged into the audio jack they work fine but unfortunately my phone doesn’t have one. Anybody that can help?