How to open compartment where battery is located

From the owner's manual:

• Open front thermostat door and open battery compartment door.
• Install two new "AA" alkaline batteries. Locate the positive (+) ends of the batteries and match them with the positive (+) terminals located in the battery compartment. Close battery compartment.

Going by the photo of the thermostat, it looks like there's a finger recess or latch on the right side of the thermostat that you pull on to swing the front open. If there is unexpected behavior from the thermostat after replacing the battery, see the reset procedure in the installation section of the manual.

Link to manual: https://thermostat.guide/proselect/proselect-pstsl21p52-2h-1c-programmable-thermostat-installation-guide/#battery-replacement

Replacing the Batteries

• Open front cover and locate the battery compartment door.
• Gently remove the two "AA" alkaline batteries located in the battery compartment.
• Install two new "AA" alkaline batteries into battery compartment. Make sure to match the positive (+) ends of the batteries with the positive (+) terminals located in the battery compartment.
• Close battery compartment. The low battery indicator should not appear in the display.

Question edited for clarity, full 'make model (what it is)'.

It may not have one

• Dual Powered - Hardwired or Battery

Their own manual is terrible, but it is Section 7 here

Replacing the Batteries 1. Open the thermostat cover and locate the battery compartment door. 2. Remove the two "AA" alkaline batteries located in the battery compartment. 3. Install two new "AA" alkaline batteries into battery compartment. Make sure to match the positive (+) ends of the batteries with the positive (+) terminals located in the battery compartment. 4. Close battery compartment and verify that the low battery indicator does not appear in the display

https://api.ferguson.com/dar-step-service/Query?USE_TYPE=INSTALLATION&PRODUCT_ID=3984136


https://thermostat.guide/proselect/proselect-pstsl21p52-2h-1c-programmable-thermostat-product-specification-guide/

..

To replace the battery on a remote, you will typically need to remove the back cover of the remote to access the battery compartment. Here are the general steps you can follow to replace the battery on a remote:

1. Locate the battery compartment: The battery compartment is usually located on the back of the remote and is typically held in place by a small latch or a screw.
2. Open the battery compartment: Depending on the design of the remote, you may need to use a small flathead screwdriver or a coin to open the battery compartment. Some remotes have a latch that you can slide to open the compartment, while others have a small screw that you will need to remove.
3. Remove the old battery: Once the battery compartment is open, you can remove the old battery by gently prying it out of the compartment using a small flathead screwdriver or a similar tool.
4. Install the new battery: Insert the new battery into the battery compartment, making sure that the positive and negative terminals are oriented correctly. The positive terminal is usually marked with a + symbol and the negative terminal is usually marked with a - symbol.
5. Close the battery compartment: Once the new battery is installed, close the battery compartment and secure it in place using the latch or screw.

If you are having difficulty removing the back cover of the remote or are unsure about how to properly install the new battery, you may want to refer to the owner's manual for your specific remote or contact the manufacturer for assistance.

Replacing the Batteries
1.Open front cover and locate the battery compartment door.
2.Gently remove the two "AA" alkaline batteries located in the battery compartment.
3.Install two new "AA" alkaline batteries into battery compartment. Make sure to
match the positive (+) ends of the batteries with the positive (+) terminals
located in the battery compartment.
4.Close battery compartment. The low battery indicator should not appear n the display

1. Locate the Battery Cover: Look for the battery cover on the back of the remote control. It is usually a small compartment that can be easily opened.
2. Remove the Battery Cover: Depending on the design, there may be a latch, screw, or sliding mechanism to secure the battery cover. Use your fingers or a small screwdriver to open the compartment.
3. Remove Old Batteries: Take out the old batteries from the battery compartment. Pay attention to the orientation of the batteries, so you know how to insert the new ones correctly.
4. Check Battery Polarity: Take note of the positive (+) and negative (-) signs inside the battery compartment. Make sure to insert the new batteries with the correct polarity to match these markings.
5. Insert New Batteries: Place the new batteries into the battery compartment, ensuring they are properly aligned with the correct polarity. Press them down gently to make sure they are secure.
6. Replace Battery Cover: After inserting the new batteries, close the battery compartment cover securely. If it has a latch or screw, make sure it is fastened properly.
7. Test the Remote: Point the remote at the device it controls (such as a Toshiba TV) and test whether it responds to your commands. If the remote is working correctly, you have successfully replaced the batteries.
8. Dispose of Old Batteries: If the old batteries are no longer usable, make sure to dispose of them properly. Many communities have designated recycling locations for batteries.

Rear Compartment Lid
The rear compartment lid can be opened by operating the rear compartment lid release switch, located on the instrument panel, or by using the manual release located on the rear compartment lid. Battery voltage is supplied to the rear compartment lid release relay through the Main Power fuse. The roof and door module (RDM) receives the rear compartment lid release request via the rear compartment lid release switch signal circuit. The RDM grounds the rear compartment lid release relay coil when a release input is received through the instrument panel (I/P) switch. Grounding the coil causes the rear compartment lid release relay to energize, providing power to the rear compartment lid latch assembly through the rear compartment lid release actuator supply voltage circuit.
As an alternate method of operating the rear compartment, an emergency release handle is accessible from within the rear compartment. When the handle is slightly pulled, it will provide a ground for the bed cover release relay which will cause the actuator to operate and open the rear compartment lid. If the handle is pulled further, it will mechanically open the lid, so even if the battery is discharged or there is an electrical concern, the emergency release handle will mechanically open the lid.

As an alternate method of operating the rear compartment, an emergency release handle is accessible from within the rear compartment.

This may have been solved by now however...
REMOVE MAIN BATTERY... Before Opening any compartments!
The CMOS battery is located in the modem compartment.
Place the unit upside cown with the rear connectors facing towards you. It is the compartment on the right rear corner (i-screw to remove). It may be difficult ro open due to the modem labe sticking to the cover. Use care when attempting to pry door open.
Battery is CR1220 0.5in Diameter (Dime Size) (40mAh Rated).
Alan

I give up...battery compartment so bad I'm returning the camera.