Aqualink problems

My T cell 15 went out after 7 years of service. Bought a new one, put it into the system, first day everything was working. Generating chlorine, the next day I go out to check it out and no lights on the control box. No power light no nothing!! I reset the breakers and changed the fuse on the bottom and still nothing. What could make it do this and any ideas what is wrong? Was told no software or anything was needed as it was a Tcell 15 for a Tcell15. Any help is appreciated, tired of tossing money at this thing and just want it fixed. Thanks