Our tankless water heater stopped working. It wouldn't even "click" which is the spark that ignites the gas. We found that the hydro generator wasn't producing any power. This video is how to replace that part. We also survived without the hydro generator by placing 4 D cell batteries in series into the system to power it while we waited for the part.
The part can be found here: www.globaltowne.com/bosch-aqua...
Apparently youtube disabled annotations so what you see is what you get now. No hope of adding notes to point out things. Sorry for things I said incorrectly. :P