I measured 250V between live and ground, and I also have 150V between neutral and ground. I also have 28V between live and neutral. When I measure the voltage between neutral and ground, the power neon comes on on the shower.
Which "ground" are you using as the reference ? If you are using the earth wire as your reference "ground" then the results in the quote above could be the result of a disconnected earth wire as well as a damaged neutral.
As it is a shower and therefore a high risk area please think about having the installation checked out by a competent electrician.
