Welcome to Pinside and pinball ownership. I would lift the playfield up to the service position where it's resting on the backbox so you can get a good look at the underside. Don't forget to remove the balls from the trough before lifting so they don't fall out and hit something. See if you can spot any loose wires, connectors that are pulled out or parts that are broken. Try moving the flipper manually, something might have been bent in the fall. If you don't see anything obvious take a few pictures and post them, someone might spot something. Good luck.

That is all that happens when I press the start button to test solenoid 23 as well. If you press the start button and the right flipper button simultaneously the car crunch flipper will fire once before the menu moves to the next solenoid. Solenoid 23 only connects power to the lower playfield, it doesn't trigger the flipper. The switch that 23 activates has a red/yellow striped wire coming from it that carries the power to the lower flipper. It connects to the lower playfield with a 4 connector plug, A9P13. You can check continuity between the plug and the switch with a multimeter and I would disconnect and re-seat the plug just to be sure it's making a good connection.

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Do you know if solenoid 23 is being engaged during game play when the lower flipper should be on? When the lower playfield should be active are the lights around the car on? You might want to follow the wires for both 23 and the lower flipper down the line and re seat any connectors just to be sure it's not a loose connection. When I tested my flipper in the solenoid test it hit hard enough to move the car back some. It may be a timing issue on when the buttons are pushed during the test but it might also mean that the flipper isn't getting as much power. Is the EOS switch on that flipper closed when the flipper is down? Does it open properly when the flipper is engaged? If the EOS switch is open to begin with the hold coil will be activated instead of the primary coil. I would think you could manually close the switch that is activated by solenoid 23 and that would allow you to test the lower flipper. Just a reminder that there is high voltage running under the playfield so don't reach in and close it with your finger, turn the machine off and wedge it closed with some wood or tape the switch closed. I don't know if it would shock you but it's not worth the risk.

Here is a thread with some pictures of System 3 eos switches for reference.
https://pinside.com/pinball/forum/topic/gottlieb-system-3-flipper-failure

You're welcome. Glad you found your issue and it wasn't something fried in the backbox. Enjoy the game.