I know my combination but my battery is dead on Amsec dl4000 safe. How do I open?

Question edited for clarity.
Question moved to home Security - Safes.

You can't. You have to open the safe with the Emergency Key, the combination Dial or in your case with the Electronic Keypad.

STEP 2 - CHANGING THE USER CODE
1-Open the safe by following step 1.
2-Press the Green set up button (Located on the
back cover or the hinge side of the back door
cover), the LCD display will turn Blue.
3-Enter your new user code (1-8 digits).
4-Press the # key.
5-The LCD display will turn Blue and show IN.
6-The LCD display will briefly show your new code.
7-Your new user code is now set to open the safe
NOTE: It is highly recommended to leave the
safe door open and practice your new code
several times before closing the door.

Manual

https://www.manualslib.com/manual/1800698/Amsec-Dl4000.html#manual

..

If you are looking for a manual for your keypad on your safe first you have to identify which lock it is. Amsec produces a few locks and there are numerous others it can be. You can call Amsec or get on there site . Or post a pic.

You can just buy a new dial.

https://www.safeandlockstore.com/products/Amsec-Star-Floor-Safe-Removable-Dial-B002000-.html

With mine, Is handle slightly loose and hanging down? Try lifting handle to move dial.

Order the amsec power override box that plugs into the small headphone jack looking hole under the keypad

I knew someone who had a locking mailbox like that with keys when pass is forgotten or battery runs down, they could open with key. He registered it as directions said to do so you could order new keys, the old mailbox was also lockable and since owner died he had to throw it away as couldn't prove he wasn't thief. Maybe something there helps.

Locksmiths agree on How to install sentury safe batteries
slide open the battery cover located just below the keypad.
Insert a paper clip or pen point into the small hole in the cover. Push in while sliding cover to the right. Disconnect and remove the battery holder. Insert the 4-batteries as indicated.
reconnect the connector and put back the battery holder. Slide the cover back in place.

Use paperclip to push in pin size hole below keyboard and then slide panel to right. Battery box is right there. Replace batteries and then was already to accept code.

I have pin code but batteries went flat while I was on holiday, how do I unlock my Hardline digital safe? I do not have override key