Furnace troubleshooting

Looking for some troubleshooting tips.

- Google nest thermostat is throwing a no power error. No common wire, but never been an issue before. Yellow, Red, white, green wires. Checked with a multimeter and I do have 24VAC across both red-to-white and red-to-yellow at the thermostat.

- Furnace doesn't have indicating LEDs but has a couple 7 segment displays. Furnace shows idl on those displays. Tried jumping red to white at the thermostat, but furnace doesn't do anything and stays on idl state.

- 5 amp fuse on the Furnace board looks intact. Furnace is in the basement, doesn't have any external float switch that I can see.

Anything I could check myself before calling a tech?

Thanks!