Juan removed the first glass door by unscrewing two bolts at top. It's on the floor to the left. Then he removed the inner door.
Then he removed the rocks and unscrewed the bolts that held the rock-pan in place.
Then he removed the rock pan.
Then he removed a metal cover that sat under the rock pan.
This is where all of the mechanical parts can be seen. Juan replaced the gas valve you can see on the lower left. And then the ignition successfully set off the flame.
After that he put everything back together and re-tested it. He turned the gas key on the right to full-on position (leftward turn). After flipping the wall switch to the on position, slowly the flame began to appear and became slowly stronger as the minutes went by.