Thanks for the advice guys.

Does anyone know how we go about warranty repairs in the UK? I have just been in touch with Nokia Care online who can't help me as they have not been trained and the warranty checker claims this is "out of warranty", although I am guessing the automated system may not be able to recognise this in the UK? I bought this from a forum member and the device was "as new" still in it original plastic packaging. As I said before, it was working when I powered it on but has become worse since so returning it would be my very last option if there is other avenues I can follow first

@requiem_76: Did you have this problem before flashing the device?