We done' use our coleman hot water on demand

If it is out of warranty there is a fuse inside them that is covered with a light rubber coating, it is the common glass style fuse. That may be causing your issue assuming the battery is ok. The batteries die regularly too especially if it hasnt been charged and is sitting around.

The Coleman website has them. Www.coleman.com Search for the HWOD product, then click Parts.

Need to restrict the water input so it does not flow through so fast

took coleman away for weekend wouldn't work. Very dissapointed, was cold would have loved a hot shower. Had charged battery, when I went to start it. It wouldn't go, light come up as battery low tried it on car charger still no luck. Got home and looked up this site told me to try taking filter off pump and putting a long nail inside to turn pump to make sure it wasn't seized. And guess what every thing works well thank god, water temp was dodgy as well but now all good. Thanks to people that do reply to these sites, it has saved me a lot of money and frustration.

You are pushing the knob inwards then turning it ?

I recall 3 and a half liters per minute. More than the Primus and the Cube

You may have blown the internal fuse. Remove side cover, locate the circuit board and fuse, replace and reseal reinstall side cover.

Blown fuse on circuit board. Take one side off, find the board. Fuse is water tight sealed. Remove the seal and replace fuse. This seems to be a rather common problem, but coleman doesn't give any help on it. There are only aprox 7 screws that hold the case together. One little one in under the decal on the front just blow the knob. THERE IS NO NEED TO TAKE THE KNOB OFF.

http://www.coleman.com/coleman/images/pdf/2300-700.pdf
Trouble shooting guide

The pump is seized or the fuse is blown.