Outdoor device won't register inside.

Question edited for a LOT more clarity. full 'make model (what it is)'.
Question moved from Computers to Model category.

Remove the batteries from both indoor and outdoor unit. Leave them out for 10 minutes. Replace the outdoor sensor with a new battery (2xAA), and then new batteries in the main unit (3xAA).

00605 Wireless Weather Station + Companion Instructions

AcuRite https://www.acurite.com > media > manuals > 0... PDF NOTE: When replacing the batteries for the wireless sensor, remove the batteries from the sensor and clear that sensor's channel on the main unit by pressing ...
6 pages

Hard Reset for Sensor Models 00606TX/06009RMA1 & ...

AcuRite https://support.acurite.com > en-us > articles > 360007...
The following reset steps can be performed to correct issues of the sensor not connecting to the display. Symptoms of the sensor not...
https://fccid.io/RNE00605TX/User-Manual/User-Manual-707183

..

Reset display by pressing the RESET button, located on the back of the display unit inside the battery compartment. Date and time will need to be entered after a reset. Flashing of the outdoor temperature is generally an indication of wireless interference.
https://www.acurite.com/media/manuals/00754-instructions.pdf
Hard Reset:

1. Bring both the sensor and display unit together and power down by removing at least one battery from each and/or removing the power cord.
2. Make sure the A-B-C switch on both units matches. ...
3. Reinstall the battery in the outdoor sensor.
4. Reinstall batteries and/or power cord into the display unit

https://support.acurite.com/hc/en-us/articles/360013641694-3-in-1-Reset

Here's the manual for the AcuRite Weather Forecaster. If it's not showing the outside temperature, make sure the A-B-C switch is set to match the display unit. Not doing so might be the reason it's not synchronizing and displaying the outdoor temperature. https://www.acurite.com/media/manuals/75077-75107-instructions.pdf

Make sure that all the batteries are good!!
This procedure outlines the typical process to pair the sensor and base.
Base Station Battery Installation
·Remove the printed vinyl label from the LCD screen of the base station
·Position the remote sensor near the base station
·Open the battery compartment at the back of the base station and insert (2) AA batteries according to the polarity markings. Replace the battery compartment cover.
·Within a short time the RF signal icon (located to the left of the outdoor temperature channel indicator) will start flashing. This indicates that the base station is ready to pick up the RF outdoor temperature signal from the remote sensor. It will continue to flash for 3 minutes or until the signal from the remote sensor is detected.

Register the Remote Sensor
·Open the battery compartment at the back of the remote sensor and slide the channel selector switch to your desired channel. For the first remote you may select any channel, for additional remotes select any unused channel
·Insert (2) AAA batteries according to the polarity markings. Be sure to install the batteries in the remote within the time that the RF signal icon is flashing on the base station. 1541 WeatherGuide Wireless Weather Forecaster with Barometer

If this is for the AcuRite weather station, please contact customer support at: http://www.acurite.com/support

We would recommend a reset of your Weather Station. Please verify that you are using a good-quality, standard alkaline battery, and follow the steps below.

1. Remove the batteries from the outdoor sensor only.
2. In the outdoor section on the main unit, there will be a "CH" and number 1-3.
3. If on CH 1, press and hold the channel button on the back of the unit for 5 seconds.
4. Press and release the channel button one time, it should show CH 2.
   • If it does not change to CH 2, repeat steps 4 and 5.
5. Press and hold the channel button for 5 seconds.
6. Press and release the channel button one time, it should show CH 3.
   • If it does not change to CH 3, repeat steps 6 and 7.
7. Press and hold the channel button for 5 seconds.
8. Press and release the channel button one time, it should return to CH 1.
   • If it does not change to CH 1, repeat steps 8 and 9.
   ***Regardless of what channel you begin on, clear out each channel by holding the channel button and return to CH 1***
9. Reinstall batteries in the outdoor sensor.
10. Press and release the TX button.
11. Leave both units side by side for up to 30 minutes to gain a strong connection.

If you need any further assistance, please contact AcuRite Customer Support at 1-877-221-1252 or [email protected].

We would recommend a reset of your unit. Please verify that you are using good-quality, standard alkaline batteries such as Energizer or Rayovac, then follow the steps below.
1. Bring both the sensor and display unit indoors and remove at least one battery from each.
2. Make sure the A-B-C switch on both units match. Sometimes changing to a different channel can help.
3. Reinstall the battery in the outdoor sensor.
4. Reinstall the battery in the display unit.
5. Let the units sit within a couple feet of each other for about 20 minutes to gain a strong connection.
If you need any further assistance, please contact AcuRite Customer Support at 1-877-221-1252 or [email protected].

Have you changed the batteries on the outside sender unit?

My outside display stopped working, but the inside display still worked. I found that one of the two batteries in the inside unit was almost all the way dead. Once I replaced both batteries the outside display worked. I also checked the batteries in the outside unit. After all batteries were installed, I pushed the small button that is inside the battery compartment on the outdoor unit. It's now working perfect..