Installing a Nest thermostat is harder than I thought

I got a 2nd gen Nest thermostat from a neighborhood garage sale. However installing the thermostat is harder than I expected. I still can't make it 100% working.

Drilling a hole

This may be obvious. I had to drill holes.

Turning-on/off an electric breaker would kill stuff

In my case, my 1st generation Echo became silent after that. Luckily it killed the AC adapter, not the device. So having a compatible AC adaptor made her alive again.

2.4 GHz WiFi

https://support.google.com/googlenest/answer/9249905?hl=en

5GHz networks are incompatible with some products. Some Nest products, like the 2nd generation Nest Thermostat and Nest Protect, only support 2.4GHz Wi-Fi networks.

This is one of the shortcomings of getting old devices in 2022, which I wasn't fully aware about.

C-Wire

This is where I'm at. My HVAC system doesn't have C-wire and my old thermostat control panel is battery-operated. However, Nest thermostats need more power and won't be battery-operated.

https://support.google.com/googlenest/answer/9251212?hl=en

Nest thermostats are designed to use very little power, and in many cases they can use your system’s heating and cooling wires to get enough consistent power. But sometimes, you may need to connect a common wire (C wire) or power accessory, like the Nest Power Connector, to make your system compatible.

Not really sure that is worth to continue at this stage to be honest.