Just sent email not sparking up!! On/off switch not lit up and what position is in the on position??

If its in its sheet metal holder and facing up it should be ok
Are you switching the red knob to pilot and holding it down keep it down while lighting and for 60 sec then let it up slowly and turn to on.. then it should stay lit and main burner should lite
Hope this helps Mike

the igniter probably did this prior to the adjustment if not check manuel if this not a safety back up to prevent gas from not being burned .

Hold in your pilot button, then push the spark button repeatedly to light your pilot. Once its lit, hold that pilot button in for 30 seconds to heat your thermocouple. once its heated, release the button, and slide the slider to burner position. Turn on hot water fixtures to get the unit to light

Copy following link to troubleshoot by type of gas control valve:
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html#intellivent
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html
http://www.thetankatwaterheaterrescue.com/forums/forum3/

Rheem does not post service manuals ... wonder if that's why huge majority of water heater problem on fixya are about Rheem/Richmond tank and tankless water heaters

Gene
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If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Sounds like you might you might have a faulty ground in the original circuit. You possibly have a solenoid that is sticking, bad ground, wiring, etc...... because of age/carbon buildup/etc. and needs replacing, or the sparking mechanism associated with the solenoid isn't sparking properly. If it is all part of the same regulator there might be a problem with gas flow through the regulator to the jets. Either way, I think I would start by looking at the solenoid, see if its replaceable by itself and work back from there. Good Luck!!

If you can't hear clicks, then very likely it is the "microswitch" that is a rectangular white plastic box that can be seen at the bottom of the unit from underneath. It's purpose is this: when there is gas pressure, a pushrod turns the switch on, thereby allowing electrical current to flow from the "hydrogenerator" to the igniter unit. The hydrogenerator generators from about 1 to 2.5 volts AC (not DC) when water is flowing, powering the generator which powers the igniter unit....assuming the microswitch is allowing electrical current (the voltage) to pass through. It is a "self-adjusting" switch because the pushrod can come out at different pressures. So if your gas fluctuates, the microswitch will be fixed to a higher pressure level, but not be able to turn on if the pressure drops. This is because the pushrod is not pushing as far. It's simple to unscrew the plastic box and push the teethed switch setting back to the initial default position, and then carefully replace the plastic cover. Then do it again next time it stops working, a year or two it seems for many people. You can take out the switch and connect it's two wires directly, but if there is no gas pressure and you let water flow through, the igniter unit will constantly be sparking and thereby might fail early. If there is no gas pressure, then maybe it is because of a local leak and thereby bypassing the switch is a built-in explosion hazard, but that would require the sparking to no longer be internal to the ignition unit.

I don't know the answer to your specific questions.
Before calling service technician, open following link for Bosch troubleshooting resources including Bosh contact information, typical manuals, error codes.
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

I would check to make sure thermocouple is in proper position in pilot flame. If so and pilot won't stay lit I would replace thermocouple. Thanks

It sounds like your main valve. The diaphram may be loose fitting or it has a small leak.

Have you checked for 12 volts DC getting to spark module ? If it's just the 2 wires going to spark module, Red and green, check for 12 volts at the red wire.
If it has the 9 wires on 2 connectors, check for 12 volts at Brown and Orange. If no 12 volts there, then you'll have to go back to switch and check there for 12 volts in and out when switch in on position. Let me know what you find.