Webasto water heater

I did the fuse thing and it started working again, however on our last trip, this last weekend, the heating wouldn't work again. We did the fuse procedure but it kept showing Error 01 no data connection, took it to the place we bought it and they checked the loom and the fuses but it wouldn't reset or work on any setting. I may be being stupid but the only thing I did different was that I filled the water tank and there was a leak underneath the van, which I assumed was an overflow, would this have caused this error? Help x      

I found that if you only remove the 15amp fuse as directed by the handbook, you get the error code 01 no data connection. If you remove all four fuses wait about a minute then replace them, the system is then ready to be reset. Try this and see if it works for you.

Thank you, I will try that in the morning, does the electricity have to be on or off please?