Triton Jade III

First check that the inlet to the shower is not blocked ,then,

Forgetting about the temperature turn the shower from fully hot to fully cold at fully hot you should have not much more than a dribble coming from the hose and on fully cold you should have a good strong flow, if you do not have this difference then you may have a faulty flow/stabilizer valve.

I think you need to replace the solenoid valve

Likely to be a faulty element however it is still under guarantee I would give Triton a ring and they will probably send out an engineer

 The pressure relief device has blown.

It’s a safety device on the bottom of the heating tank or outlet pipe

It is fairly easy to replace however there is usually something that causes it to blow,

often a kink in the hose or the showerhead is blocked, so check this before fitting the new PRD.

http://www.showerdoc.com/TRITO-83301330-PRD-(Pressure-Relief-Device)-and-'O'-ring-(Pair)?ss=prd&pg=2

http://www.showerdoc.com/trito-82800450-triton-pressure-relief-device-82800450

Video re replacing the outlet pipe PRD

http://www.youtube.com/watch?v=2B1Tg7XXKtE