Basement flooded, combustion air flap employed.any way to repair?

Replace flooded water heater
http://waterheatertimer.org/Flooded-water-heater.html

Troubleshoot by type of gas control valve
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html#intellivent

gene

Water Heater Timers Save Money

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

Most likely: Combustion chamber got too hot because air intake is clogged with dust, causing less air to flow upward through vent pipe ... the slowed flow of air caused combustion chamber to overheat.

What brand and model water heater?
Look at label on side of unit and add comment.
Otherwise call service tech to repair/ replace water heater and clean arrestor screen (air intake) and replace or reset parts as needed, depending on model number and brand water heater.

AO Smith, Bradford white, and Rheem are main manufacturers.
Each has slightly different repair protocol, and each gas control valve can also be different. So more information is needed.

Identify gas control valve:
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html#intellivent
Rheem TRD/ FVIR glass vial
http://waterheatertimer.org/How-to-repair-Rheem-FVIR.html
How to remove combustion parts to inspect for Rheem glass vial and clean arrestor screen located under combustion chamber:
http://waterheatertimer.org/How-to-replace-thermocouple.html

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

Open following link for troubleshoot error codes showing 7 flashes on Honeywell gas control valve is system lockout due to flammable vapor:
http://waterheatertimer.org/pdf/Honeywell-gas-control_error-Damper-series.pdf
The FV system in Rheem can be tripped by presence of flammable vapors such as gasoline or paint fumes etc, or it can be tripped if water heater was dropped, or mis-manufactured, or if gas control valve is defective, or if water heater is not getting adequate fresh air, or there is inadequate venting of combustion by-product.
When combustion chamber overheats, then glass vial breaks and damper shuts off air supply to water heater and it will not light.
Open following link for possible help fixing the problem:
http://waterheatertimer.org/How-to-repair-Rheem-FVIR.html

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

Open following links to help identify product and download typical manual:
http://www.rheem.com/Products/tank_water_heaters/gas_water_heaters

http://www.rheem.com/product.aspx?id=CC643E03-4C15-4775-B139-E504A95651F7

Typical manual:
http://globalimageserver.com/fetchDocument.aspx?id=01091171-3bac-4cb9-a0a8-a11aac3bd668

Usually, the instructions for lighting water heater are on side of tank, and located at gas control.
If you add a comment and describe gas control in detail, and add if model has piezo igniter, I might be able to provide specific instructions for that gas valve.
Also include if wires on bottom of gas control go to a switch located on combustion door.
http://waterheatertimer.org/images/IMG_9146-gas-control-thermo.jpg

Make sure basement has plenty of fresh air to support combustion.
Clean combustion parts and air intake.
Check that thermocouple sits inside pilot flame.
If no gas comes out of gas control when trying to light water heater, then check that gas valve handle is parallel with gas line. Gas pressure might be low. Gas might have air in line.
If pilot lights but will not stay lit, then thermocouple might be bad.
http://waterheatertimer.org/pdf/How-to-replace-thermocouple.pdf

Many factors can contribute to water heater not lighting or staying lit.
Get started, and then add a comment with steps taken so far, and what you observe for more help. I will be here most of the evening. Aug 1, 2011.

Take a moment and rate answer:
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.

Burner parts need yearly cleaning, air intake needs periodic cleaning, burner parts cannot be exposed to trace amounts of chemical without damaging parts, no water should be dripping down from vent, vent should be checked for updraft, ample combustion air is required especially in closed basements, tight houses, and hot attic, bleed gas line to remove air, check that gas control thermostat is functioning.
Open following links for pilot light help:
http://waterheatertimer.org/How-to-install-gas-water-heater.html#troubleshoot
http://waterheatertimer.org/pdf/Pilot-light-will-not-stay-lit.pdf

Manufacturers say to replace water heater after a flood.
Flooded water heater can be repaired by replacing parts but warranty is voided.
And if water heater reached gas control valve, then gas control has to be replaced >> possibly the gas valve eco tripped.

I don't know how effective cleaning burner parts will be, since a small spider wed inside some of those tubes can cause water heater not to function. Small obstructions cause big problems.
I'm sure the plumber cleaned it out real well.
Find manufacturer using label on side of tank, find manual with parts diagram, and order burner parts.
http://waterheatertimer.org/Water-heater-manufacturers.html

It might be cheaper to install a new water heater yourself from box store
http://waterheatertimer.org/How-to-install-gas-water-heater.html

I read one article:
http://www.diychatroom.com/f7/rheem-hot-water-heater-pilot-burner-not-staying-lit-65755/
Guy has water heater that filled with water.
He says: "I decided to feel around. As soon as I put my finger into the hole under the burners I hit water. The air intake passage was filled with rain water, effectively chocking off the fresh air. A few minutes with a siphon tube cured the problem and the water heater works normally again."

Absolutely feel obligated to upvote the help.
Or 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.

Call your gas company and have them check out the unit.

make sure you have the proper piping for out side combustion air. this is a code in some areas?? this will help dispate the gas smell after the water fires up and causes the gas smell... also might check the flue make sure it is properly installed and venting properlymm

tank looks to be leaking and getting the insualtion and floor wet .. so replace water heater?? Once the tank is leaking there is no repairing it..

Was the gas valve under water? If so it must be replaced. If not, and you're sure you are holding in the button for at least 30 seconds after the pilot is lit, the pilot will need to be removed disassembled and cleaned. Also, the thermocouple may or may not be bad, replace it anyway (for the cost @ Lowes etc just not worth it).