What's up with My Bosch Hot water heater??

possible faulty pressure switch connected to the water line and that is failing to turn on the main gas tap solenoid
best have it checked by an accredited gas fitter or service center for the make

What leads you to suspect that pilot blew out instead of another problem?
Fact that pilot will not relight, indicates other factors at play.

Open following link for Bosch troubleshooting resources including manual, and Bosch contact info:
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

Best place to start is your manual.
http://waterheatertimer.org/pdf/Bosch_10P-installation.pdf

1) Manual recommends 'cleaning by authorized person, never less than once a year.'
Tankless water heaters, and most newer tank-type gas water heaters, are highly technical and finicky devices that require continual maintenance, with tankless requiring 'yearly' maintenance while tank-type require 'periodic' maintenance.
2) Troubleshoot in manual says 'no gas supply' or 'blocked pilot' replace pilot injector

Upvote the help.
And take advantage of fixya expert assistance live.
For a price, expert works with you while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

Consult your owners manual.
http://www.bosch.com.au/content/language1/downloads/70R_UserManual1023.pdf
Heres a new one if you don't have or lost yours. You can't, you got bad advice. tankless system don't have a running pilot light. They operate by detecting water flow and then turning on. Many also state on the lighting instructions to NEVER try and manually light the pilot. Try Bosch tech support. Lowes sells Bosch heaters and they might be able to help you get the support number faster. Hope this helps but please don't go sticking a flame inside there.

No, I do not know.
Open following link for Bosch troubleshooting resources.
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html
Tankless require yearly maintenance as covered in manual. They require correct venting, gas pressure and/or electric current, they require specific incoming air quality, incoming water pressure and flow, and can stop working with basic electric problems, plumbing problems due to check valve or sediment blockage in line, or single-handled faucet crossover, and the myriad of sensors and parts each work together in a specific pattern that can be interrupted by any small or large failure, or by multiple half-failures. As a general rule, repairs are not do-it-yourself, and each part has an installation protocol. But it's supposed to last 20 years, while the maintenance, parts and service will exceed the expected 1-8$ per month savings.

Solve problem for 317$ at Lowes:
http://waterheatertimer.org/How-to-install-gas-water-heater.html
Do yearly maintenance, and this too will last 20 years with cheaper parts and cheaper overall cost, since all costs are energy.

Open following link for Bosch tankless troubleshooting resources, including Bosch contact information, typical manuals, error codes, tech support, parts, fuel-saver calculator, service bulletins, water heater forum, fixya links, disclaimers, and links for finding service technician.
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

Before calling service technician, read manual for fault finding and possible solutions.
Read manual cover to cover, make sure tankless receives yearly maintenance as outline in manual.
http://waterheatertimer.org/pdf/Bosch_water-wizard.pdf
http://waterheatertimer.org/pdf/Bosch_13P_16P_In.pdf

Following links talk about keeping pilot lit, and describe location somewhat. Bosch water wizard has standing pilot light.
http://www.fixya.com/support/t2961646-water_wizard_10p_pilot_light_keeps_going
http://www.fixya.com/support/t2960079-bosh_water_wizard_10p_pilot_light_keeps
http://www.fixya.com/support/t6182021-bosch_10p_tankless_hot_water

1) The manual does not show diagrams you asked for.

2) Website that sells Bosch parts does not show parts for water wizard, nor does Bosch site for parts: Instruction manual says: replace pilot injector
http://www.boschhotwater.com/HelpfulResources/PurchaseParts/tabid/837/Default.aspx
http://www.houseneeds.com/shop/heatingproducts/waterheating/parts/bosch2400espartsbuy.asp#

3) Searching "pilot injector for Bosch Water wizard" turns up fixya questions which is generally bad news for do-it-yourselfer because it means information sources are through service technician.

4) As a general rule, tankless are not do-it-yourself repairs or installation because they are affected by so many internal and external factors, including air quality, air flow, venting, other gas appliances, gas pressure, gas supply, water pressure, water flow, plumbing problems, water quality, plus internal parts and including any combination of things listed above..
Replacement parts each come will disclaimer.

Add a comment with your experience so others with same-similar problem can benefit.
Send some photos so the internet can see the problem.
http://www.fixya.com/support/r6568559-post_photograph_fixya_questions_answers

Also take advantage of fixya expert assistance live.
For a price, expert works with you while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

I have the same problem with the same model. The problem has been identified by a friend of mine, correctly, I think.
This is a very dangerous problem involving Bosch's much touted safety feature, ironically enough. IT IS THE FLAME SENSOR IN THE GAS VALVE. The flame sensor is supposed to confirm that the pilot has lighted BEFORE the main gas line sends gas to the main burners, after which the pilot shuts off. The pilot light is not coming on, the sensor that shouldn't let gas fto the main burners is failing and the main gas is flowing and ignighting from the spark that is supposed to light only the pilot in a big explosion.
This is the 2nd unit of this model that has failed. I think Bosch should do a recall

may require gas to to be purge leave to expert

get a long stick match, a flashlight remove lower inspection cover, find thermocouple and pilot light will be next to it,turn gas valve to pilot light and hold down,stick the match in by thermocouple till the pilot lights and hold valve down till pilot stays lit,this may take a minute or more,then release gas valve and see if pilot stays lit, if not retry,if it wont stay lit,the thermocouple is defective and needs replacement

You need a new thermocouple. Its the little stick like thing that the flame heats up to tell gas valve to open.

Thermo coupler may be defective. it controls the main gas valve by closing main if pilot is out. make sure thermo coupler bulb is positioned over and near tip of pilot flame, but not in the flame. Thermo couplers are inexpensive and easy to change out.