Water Heater exterior is on back wall....so plumbing lines (cold in/hot out and bypass if it has one) would be directly opposite-------Under Oven/Under Kitchen Sink
That panel under oven is probably removable
If water heater is 'bypassed' you WILL get flow out of Faucet hotside
If water heater is NOT 'bypassed you will get flow out of Faucet hotside
You can pop open the Water Heater T&P Relief Valve (outside compartment) but should only be done to check for water in WH Tank
Should bleed air out of hotside using kitchen faucet so 'air pocket' in WH Tank is formed and not disrupted (which can happen using T&P to bleed air out when filling)