proform 450cx repair required?

been using the unit successfuly since the new year, ahve used silicone spray to lubricate the running deck. Then today having finished a 8k run, it blew the trip switch, i reset it, turned it on ans it blew the 13amp fuse in the plug. Replaced the fuse, switch it on no issues, all lights come on, but as soon as you press a speed/programme button it blows the fuse again.
Any one any idea, or can recommend engineer local to Exeter EX14 postcode, seems ashame to ditch it, but Proform quoted £90+vat for call out and £300+vat for a new board, not sure how they can make that assessment over the phone?
Would rather put £500 towards a new one than get ripped off...
thanks,