never you asked about Modal. yes it can be dyed. its a sort of rayon. I think , the Hush shorts I dyed were modal and have taken colour really well. I'd give it a go anyway !
if its Black use Dylon darkest black to redye..
But I'm not sure about your washer/dryer though given cherries experience .. My machine is just a washer.
nearly please do post a photo of that Boden scarf when you get it ..I am wavering..