2007 renault megane 1.5 dci

Hi guys I've got a 2007 renault megane 1.5 dci the first night I had it the battery went dead there's a buzzing noise coming from the back of the engine bay begone the steering wheel I can see it it looks like it's something to do with the breaks because of the pipes going into it and I've got break fault and abs light on I've plugged it in but only fault showing is the glow plugs any ideas? Tia