Sennheiser HD 450bt stopped working?

hi i’m at a loss so wondered if anyone on here knew anything. i used my headphones earlier this morning they were fine, now when i turn them on they refuse to pair. they say power on, flash like two times then remain blue. then after turning them on they don’t turn off they just keep saying power on. i can’t seem to reset them either? just nothing works. they work when i use the cable but i don’t have an audio jack in my phone. is there any way to fix this or will i just have to send them back?:( any help appreciated:)