My SP4 isn't working, I have to wait to get home to try a few things Gary suggested but odds are good the controller is dead. It's still under warranty, I've only had it a week, but warranties take time and that's my problem.
I work odd hours, I don't drive and there is no public transit in the morning when I leave home. I can't pedal to work anymore, it's mostly uphill and living in Nfld means there is a 40km/hr headwind pretty much every day. So I taxi. $120 a week in taxis. I can buy a new controller for $87.50 and ship it overnight for $40, that's about what I'd spend in taxis for a week and I'm sure the warranty process will take longer plus there are shipping costs with that too.
So how hard is it to swap the controller? Can I do this myself? I'm pretty handy with a soldering iron, I've built numerous guitar pedals and other simple projects as a hobby. Would I be able to do this myself?