Changed battery in my safe DS 3607 and don't remember combo what is factory five digit code to open

As far as I am aware there is no such thing as a Factory Reset Code otherwise every burglar in the world would be using it. You can ask Sentry Safe, but they charge and you need a signed affidavit that the safe is yours, and the serial number, BUT your husband has changed it.

You can use the key to open it, they all have a key in case the battery goes flat.

Or you can just open it with a rare earth puck magnet. They are not at all secure!

https://www.google.com/search?q=Sentry+Digital+Safe+open+without+tools

..

See if this works:
How do you reset the code on a Sentry safe? How to Reprogram a Sentry Safe

1. Press the "Prog" key on the keypad.
2. Enter the five digit pre-set factory code twice. ...
3. Enter a new five digit personal access code of your choice. ...
4. Delete the personal access code by pressing "Prog" key and entering the five digit pre-set factory code twice.
5. Press the "Prog" key on the keypad twice.

To reset the combination on a Sentry safe, open the door of the safe, delete the existing codes, press the PROG or P key and enter the factory code. Finally, enter a new five-digit number as per individual preference, which is the new user combination.
It is always prudent to reset the combination on a Sentry safe when the door is open because it prevents the user from being locked out. To open the Sentry safe door, type the five-digit factory code given in the owner's manual. This factory code cannot be altered.
To delete the existing codes on newer models of the safe as of 2015, press the P button. Then, type the factory code and follow it up by inputting "00000" into the safe. On older models of the Sentry safe, press the PROG button and type the factory code two times.
After deleting the existing codes, press the PROG or P key and then enter the factory code once again. Within five seconds, type a new five-digit number, which is the new user code. To verify if the user code is working, retype it and then close the door of the safe. The user code is the primary code for opening the safe, and users can reset it as often as they want too

Open your Sentry safe by typing the five-digit factory code (found in your owner's manual) on the keypad. It's always a good idea to change your combination while the safe is open, so that you don't inadvertently lock yourself out.

Delete any existing codes by pressing the "P" key and entering the factory code, followed by "00000." On older safes, press the "PROG" key and entering your factory code twice to delete old codes.

Press the "PROG" or "P" key again on your Sentry safe's keypad.

Enter your safe's five-digit factory code.

Enter a five-digit code of your choosing within 5 seconds. This is your user code. While the factory code cannot be changed, your user code can be changed as often as you like, and that should be your primary code to open the safe. Only you should know your safe's factory code.

• Open your Sentry safe by typing the five-digit factory code (found in your owner's manual) on the keypad. It's always a good idea to change your combination while the safe is open, so that you don't inadvertently lock yourself out.
• Delete any existing codes by pressing the "P" key and entering the factory code, followed by "00000." On older safes, press the "PROG" key and entering your factory code twice to delete old codes.
• Press the "PROG" or "P" key again on your Sentry safe's keypad.
• Enter your safe's five-digit factory code.
• Enter a five-digit code of your choosing within 5 seconds. This is your user code. While the factory code cannot be changed, your user code can be changed as often as you like, and that should be your primary code to open the safe. Only you should know your safe's factory code.
• Retype the user code to verify it is working, and then close the safe.

[PDF]Cannon Safe Owner's Manual

https://www.cannonsafe.com/media/manual.../CannonOwnersManual.pdf

*EMP Lock is not available to retrofit on other safes; not sold separately. Page 9. Page '. 7. NL Lock. Programing the lock. Step 1. Open the safe door (factory code is ... Low Battery Warning: The lock will repeatedly beep during unlocking.

Opening a Cannon Safe with S&G lock set on factory combo ...

? 0:41
https://www.youtube.com/watch?v=XlYxrWhSLwE
Nov 6, 2008 - Uploaded by gunsafeman
opening a Cannon Safe with combo of 1,2,3,4,5,6 #

The safe can be opened using the factory set 5 digit code found on the documentation that came with it. You can also call 1-800-828-1438 with the serial number and get help.

Press: Program 2x, enter a digit user-code (green led remains on), enter the 5 digit user pin (of your choice except 00000). After 5 digits entered, the green LED turns off.

I have a different model but I had the same problem. Called customer service and they had me push up on the handle and enter the code. That didn't work but then they had me tap the safe with a rubber mallet 5 times above the panel and 5 times to the right of the panel. That worked for me. Hope one of those works.

Hi,
here is the customer service phone number for you. I am sure they will be able to help you. 800-828-1438