Did I blow my system?

I was following the instructions in this thread: https://www.reddit.com/r/smarthome/comments/vgoaa6/im_not_good_with_electrics_at_all_i_think_this_is/

as I also have an old t202 I am looking to switch to an ecobee/smart thermostat.

Here’s the sequence of events:

1. I cut the power to my thermostat via electric breaker box.

2. I opened up my t202.

3. I toggled the switch from 120v to 24v. (major brain fart given the instructions in the other reddit thread but I figured you could just toggle it, idk Im just a gir)

4. I turned the power back on to my thermostat.

5. Smoke and popping.

6. Cut the power back off via electric breaker box.

7. Switched the voltage back to 120v.

8. Turned the power back on.

9. T202 will not display anything.

I know this is karma for trying to be Barb the Builder, how should I proceed…?

And how would an electrician proceed since I presume I’ll need to hire one to fix this misfortune I have inflicted on myself. It’s not super cold in Chicago rn but not warm enough to go very long without a working hvac system.

Thanks in Advance!!