just installed a honeywell t9, followed all steps, but it says "welcome" and won't do anything else

Diagnosis

The "Welcome" screen on a Honeywell Home T9 (RCHT9610WFSW2003) is the initial boot sequence. When the device hangs on this screen and refuses to progress to the "Language Selection" or "Equipment Setup" phase, it typically indicates a "soft lock" where the processor is waiting for a specific hardware trigger or a stable power handshake. In many cases, the capacitive touch interface is not registering the user's input because the factory-installed protective plastic film is still covering the screen, or there is a static charge buildup on the display panel. If the screen is completely unresponsive to touch, the root cause is often an insufficient 24VAC power supply. The T9 requires a consistent C-wire connection to power the Wi-Fi chip and the backlit display simultaneously. If the thermostat is attempting to "power steal" from the Rh/Rc lines without a dedicated C-wire, the voltage may drop just enough to light the screen but not enough to initialize the logic board, leaving the device frozen on the boot image. You can confirm this by checking if the screen flickers when the HVAC system kicks on or if the device restarts randomly during the setup process.

How to Fix It

To resolve a frozen "Welcome" screen and complete the initialization, follow these exact steps:

1. Carefully peel off the clear protective plastic film from the face of the T9 display. Even a thin layer of factory plastic can interfere with the capacitive touch sensors, preventing the "Next" or "Continue" commands from registering.
2. Perform a hard power cycle. Go to your electrical panel and flip the breaker for your HVAC system to the OFF position. Wait exactly 60 seconds to allow the internal capacitors in the T9 to fully discharge.
3. Flip the breaker back to ON. Once the "Welcome" screen reappears, firmly press the center of the screen. If it does not advance, try tapping the very bottom edge of the display where the "Continue" prompt typically resides.
4. When the setup wizard begins, navigate to the "Equipment" section. Ensure you select the correct heat pump or conventional furnace configuration. If you have a heat pump with auxiliary heat, ensure the "O/B" terminal is correctly identified in the software settings, as a mismatch here can cause the system to hang during the final "Testing" phase of the setup.
5. Connect to a 2.4GHz Wi-Fi network. The T9 often struggles with 5GHz bands during the initial handshake; if your router uses a combined SSID, temporarily split them or use a guest network to ensure the device completes the registration process.

If That Didn't Work

• Verify the C-wire connection. Remove the T9 faceplate from the wallplate. Ensure the blue (typically) C-wire is inserted fully into the C terminal and that the copper is stripped exactly 1/4 inch. If you do not have a C-wire and are using a C-wire adapter (Power Extender Kit), ensure the adapter is wired correctly at the furnace control board. Without a stable 24V common, the T9 will frequently freeze during the "Welcome" or "Connecting to Wi-Fi" stages.
• Check for a "blown" 3-amp or 5-amp fuse on the HVAC control board. If a wire touched the chassis during installation, the fuse may have popped. This allows enough residual power for the screen to light up via the Rh wire, but not enough to run the processor, resulting in a frozen "Welcome" screen.
• Perform a Factory Reset via the physical buttons if the screen remains unresponsive. While the device is powered, remove the faceplate and look for the reset pinhole or button sequence (depending on the specific hardware revision). Hold the reset for 10 seconds to clear the NVRAM and force a clean boot.
• Test the voltage with a multimeter. Set your meter to AC voltage and measure between the R and C wires on the wallplate. You should see a reading between 24VAC and 28VAC. If the reading is below 22VAC, your transformer is underpowered or failing, which prevents the T9 from exiting the boot sequence.

Heads Up

• Avoid using "wire nuts" on the thermostat backplate; use the provided push-terminals to ensure a tight, vibration-resistant connection.
• Never touch the screen with wet hands or conductive gloves, as the T9's capacitive sensor is highly sensitive and can trigger "ghost touches" that disrupt the setup wizard.
• Ensure your smartphone is on the same 2.4GHz network as the thermostat during the initial pairing process, or the Honeywell Home app will fail to find the device even if the thermostat says it is connected.
• If you are replacing an older Honeywell model, ensure you have cleared the old settings from your account in the app before adding the T9 to avoid "Duplicate Device" errors.