Can't turn off beep sound on keypad of my stack-on Security Safes Electronic Lock for a 16 gun safe

You just buy another one, they are 50 bucks new.

Or contact Sentry Safe and see if they will sell you one.

Or take it to a locksmith and they will order and fit one for 75 bucks.

SentrySafe® Official Site ' Gun Safes & Fire Safes

Sentry Safe https://www.sentrysafe.com SentrySafe offers a broad range of secure storage solutions to keep your valuables protected from unexpected perils, theft and more. View safes.

‎Safe Selector · ‎Fire & Waterproof Safe · ‎Check Your Electronic Fire Safe · ‎Contact Us
To buy a new one.

https://www.google.com/search?q=sentry+1100+safe

..

They all have model numbers, but these should help as the procedure is basically the same

OPERATING MANUALS

https://images-na.ssl-images-amazon.com > images
PDF
OPERATING MANUALS. For Safe Models: Brigadiere 7550 Key Lock Rifle/Gun Safe. Overlord 7600 Digital Lock Rifle/Gun Safe. Quarter Master 7650 Digital Lock ...
28 pages

OPERATING MANUALS - Overstock.com

https://www.overstock.com > pdf > mastermanual
PDF
OPERATING MANUALS. FOR SAFE MODELS: 7550 Supreme Rifle Safe. 7650 Paragon Lock & Safe Home Security Personal Safe. 7501 Paragon Lock & Safe Electronic 5 Gun ...
27 pages

WALL SAFE OPERATING MANUALS FOR:

https://secure.img1-ag.wfcdn.com > 7750 manual
PDF
BEFORE USING YOUR SAFE: 1. First, Insert the key into the keypad and turn clockwise to open the door. IMPORTANT: Do not store the keys inside your safe!
Missing: drop ‎' Must include: drop

• 
  

  SureDrop 7875 Digital Keypad Depository Safe

  https://secure.img.wfcdn.com > docresources
  PDF
  Simple programmable Electronic Lock with buzzer and LED. 3 to 8 numbers ... NOTE: This safe stores up to 2 passcodes (a user code and a manager code).

children are denied access to fire arms
the fire arms are stored in one place under lock and key
the safe is mounted by bolts to a wall and cannot be easily stolen
it is a requirement under law to have the fire arms controlled
being under lock and key , it acts as a deterrent so that people with anger management problems have no legal claim to say it was an "involuntary act" when removal of life is committed

http://s3.amazonaws.com/stack-on-production/downloads/62/Elite_Manual_-_Electronic_Lock.pdf?AWSAccessKeyId=08CNY13ZYZNXTVEEJX82&Expires=1413690335&Signature=1JTuTtTym%2F06NzYkH9fS4kIbi6M%3D

Generally, In these kind of safes you follow this procedure.
1. Punch in your code.
2. Press the # button.
3. Safe gives a beep sound.
4. Turn the handle to lock position.
5. To open also similar procedure to be followed.

http://www.stack-on.com/pages/instruction-sheets

look for :Security Safes Electronic Lock Instruction Manual

i forgot my stack-on gun safe password and no key

Contact the people you bought it from or try dynamite

How to open electronic sentry safes.

Locksmith opening instructions manual for sentry fireproof electronic security safes. Insert the tubular sentry key into the lock to the left of the key pad. Turn the key all the way to the right until the plunger pops out. Press the five-digit factory code. The green Proceed light will come on. Pull the handle down; to crack the sentry door open.