changed batteries in thermostat and now nothing works

Have you changed batteries in thermostat and now nothing works? Maybe you searched through the internet and found that the solution to your problem is to replace the batteries.

However, the situation has become bigger than you expected. What else can you do now?

By the time you are through with this piece, you should be glad that your issue will be a past tense.

If you changed batteries in your thermostat and it failed to work, it could be due to a wrong installation of batteries, or the batteries you are using are incorrect. You will need to remove the battery lid and check if you installed the batteries correctly.

If yes, ensure that their voltage is according to the recommended one on the battery compartment.

Reasons Why Your Thermostat Fails to Work after Changing the Batteries

Several reasons can cause a failure of your thermostat to work after replacing the batteries.

The common ones include:

  • You did not install the batteries correctly.
  • You are not using the correct battery type.
  • One battery is old, and the other is new and charged.
  • Your thermostat has grown old.
  • The circuit breaker is tripped.
  • You have a blown fuse.
  • The furnace door is incorrectly closed.

Note: Each thermostat has different instructions to replace batteries. Kindly check your user manual to confirm the same and avoid issues that may occur thereafter.

Now we can see how you can deal with this problem.

What to Do if You Changed Batteries in Thermostat and Now Nothing Works

changed batteries in thermostat issue fix

You can apply several solutions to this problem. Kindly try each method below until your thermostat works again.

Fix #1: Check If You Installed the Batteries Correctly

One common reason your thermostat will fail to work even after replacing the batteries is the wrong installation of the batteries. You cannot install the batteries in any way and expect your thermostat to work.

You will have to get to the battery compartment; that is, remove the faceplate and check the position of your batteries.

Once you open the faceplate, you will always see marks or arrows showing how the batteries should face. The terminals should be in their correct position. If you installed them wrongly, kindly rectify them.

Fix #2: Ensure that the Batteries are the Correct Type

replace thermostat batteries

Incorrect batteries will not work in your thermostat. Note that if the batteries do not have the recommended voltage, they cannot power the thermostat.

It’s advisable to find out the required battery voltage your thermostat needs in the battery compartment.

Also, you should note that your thermostat cannot accept any battery brand.

It would be best you acquired the same batteries that came with your batteries when you first installed the thermostat. Most thermostats use AA or AAA alkaline batteries.

If you compare both and see a loop, kindly get the required batteries, and your thermostat will work as it is supposed to.

Fix #3: Replace All Batteries Simultaneously

One thing about most devices that use batteries is that you cannot replace one and leave the other.

If you change one for a new one and the other is old, your thermostat will not work.

Remember, these two batteries do not have the same power level, so they can never function properly. You will need to insert a new pair of batteries at the same time and check if your thermostat works well again.

Fix #4: Reset the Thermostat

reset the thermostat

Maybe you could be asking, do you have to reset the thermostat after changing batteries? The answer is no. You may only need to reset it if it has issues that require a reset.

Factory resetting your thermostat settles lots of issues inside it. Even though it takes back your thermostat to default settings, it is a sure way you can try to fix any trouble in your thermostat.

Here is how you can reset your thermostat:

  1. Set the thermostat to off mode.
  2. Push the faceplate inside from its sides so that you can remove it.
  3. You will see the batteries; kindly remove them.
  4. Reinsert the batteries but oppositely keep them for around 5 seconds.
  5. Then correctly reinsert them.

Your thermostat’s screen should light up to show that the thermostat is ready to work. Replace the battery’s lid and ensure that it is secure in place.

Fix #5: Check the Circuit Breaker

At times you could be fixing the batteries, yet they are not the exact problem you should address. Your thermostat circuit breaker could be having some issues.

During a power outage or an electric overload, the circuit breaker trips off. So, if you are not keen to check the breaker, the thermostat will not work no matter what else you do.

Also, the fuse might have blown; hence you will need to replace it even as you flip back the thermostat breaker.

Fix #6: Shut the Furnace Door Well

If you do not close the access door well, the door switch on some thermostat furnaces will not work well. Hence, other systems will not perform as needed.

Also, since the switch is not depressed, a power supply will not be available on the thermostat.

So, you will need to confirm if you shut the mentioned door well and, if not, kindly correct it.

Fix #7: Inspect the Thermostat

inspect the thermostat

For some thermostats such as Honeywell, you must remove them from the wall to replace the batteries.

During this process, the wiring may be deterred or disconnected from their respective terminals.

You will need to remove the thermostat from the wall again. Inspect if there are any bare wires or any of them is hanging or disconnected. If so, kindly return them to their position and ensure that each is secure in each terminal.

Fix #8: Replace the Thermostat

Like most electric devices, your thermostat is prone to many hitches, and growing old is not an option for it.

How long have you stayed with it? Most thermostats can stay up to around eight or ten years. If yours is past these years, you may need to consider a replacement.

Also, the longer a device stays, the more its parts grow old and weary too. Hence, they fail to function.

Fix #9: Contact Support

Have you tried the above troubleshooting tips, but nothing has worked?

And is your thermostat still in valid warranty? If so, it is high time you contact your thermostat’s customer support.

Your HVAC system could be having an issue that you cannot solve. So, the only solution is the experts or the makers of the same.

Read Next: Why is Heating Still On When Thermostat is Off?


When you change your thermostat batteries, and nothing works, you may need to confirm if you installed the correct battery type. Ensure that they are both new and charged and have the recommended voltage. If nothing works, check the thermostat breaker and flip it back.

Also, confirm that the device has no wiring issues.

If you changed batteries in thermostat and now nothing works, it could be due to any of the listed reasons above.

However, you don’t need to worry since we have accompanied the reasons with fixing methods. Yours is to apply the relevant solution and get your device to its proper working.

Nicole B