Need help with thermostat install

Ive attached photos of the thermostat now wiring as well as far as how it’s connected at the control board. On the board I traced the 4 wires… the wires are wirenutted into pigtails that had spade connectors to the board. Green to green plugged into G on board red to red(plugged into R on board) the yellow is connected to the white (plugged into the W on board ) and the blue from thermostat is connected to a red wire (I believe it’s one of the two wires coming in from the outside unit)

I do know I need the C adapter per app recommendations And the fact if I wire the thermostat without the adapter I get no power …any suggestions?

The wire insulation at the thermostat is a bit cracked, hopefully you have some slack on the wires to be able to trim them back to where there is good insulation, otherwise when you move them to install them in the new thermostat, you might get a short circuit. You can try protecting them with good quality electrical tape (3M scotch 33+ is recommended) if you can’t get to good insulation. Low quality electrical tape will eventually fall off and cause a short circuit, so don’t use the cheap stuff.

In your case, C is the large blue wire connected to the white wire that runs to your outdoor A/C.
Here’s a custom wiring diagram for your system: