How to unlock my assurance wireless SIM card and I can’t turn the phone off without taking the battery out

You can't. You can only get the SIM Lock code from the company that owns the phone that you are trying to put the wrong SIM card into. They do it to stop you using it because they own, or used to own the phone on a 2 year contract. The other reason is because the company thinks the phone has been stolen. You need that company to unlock it to their network, so anyone can use it, or you can sell it. This tip I wrote explains in full.

https://www.fixya.com/support/r26056685-phone_asking_puk_code

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TracFone Wireless, Inc. Unlocking Policy TracFone is working with manufacturers of mobile wireless devices to pursue secure solutions which would allow for unlocking of devices without jeopardizing the security of those devices. TracFone will use commercially reasonable efforts to ensure that mobile wireless devices are capable of being unlocked domestically without compromising TracFone's ability to protect against unlawful distribution and use of such devices and without impeding TracFone's ability to protect its intellectual property. It will continue to keep the FCC apprised of these efforts on a quarterly basis. Once it achieves this capability with any given device, TracFone will permit its prepaid customers, upon request, to unlock such devices one year after initial activation, consistent with reasonable time, payment, or usage requirements. Currently, TracFone offers a Bring Your Own Phone program which enables consumers to utilize their own wireless devices, including unlocked devices, with TracFone's prepaid service.
1 In Cell Phone Unlock Codes CellphoneUnlocker com

http://www.net10.com/faqs/troubleshooting/sim.jsp
Troubleshooting / SIM Card Q. What should I do if my phone displays "Enter PUK code"? A. The "Enter PUK code" message means that the SIM card is blocked. Please call our Customer Care Center at 1-877-TEN-CENT (1-877-836-2368) so that a representative can assist you with unlocking the SIM card. Q. What should I do if my phone displays "Insert SIM"? A. Please insert the SIM card into the back of your phone or make sure that the SIM card was properly inserted. Q. What should I do if my phone displays "SIM Card Rejected"? A. This message appears when a SIM card from another phone is used. Please make sure to insert the original NET10 SIM card included in the phone package. Q. What should I do if my phone displays "SIM Blocked"? A. The SIM Blocked message means you attempted to change the settings on the SIM card too many times. Please call our Customer Care Center at 1-877-TEN-CENT (1-877-836-2368) so that a representative can assist you with unblocking the SIM card. Q. Why does my phone display "No service" or "Unregistered SIM"? A. When your NET10 phone is turned on, you may receive this message because your phone has not yet been Activated. Disregard this message. It will disappear once your phone is active. Q. Why does my phone display "SIM card registration failed"? A. When your NET10 phone is turned on, you may receive the message "SIM card registration failed" because your phone has not yet been Activated. Disregard this message and clear the display by pressing the navigation key, which is the button below the display.

Free Samsung Unlock Codes . SGH-A300 SGH-A400 SGH-A800
Take the SIM-card out. It's important that the SIM card IS NOT in the phone, during the following steps!!
Turn on your phone without the SIM-card
Enter *2767*637#
Insert the new SIM-card, and see if it is unlocked
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SGH-E330 SGH-E500 SGH-E700 SGH-E710 SGH-E715 SGH-E720
Take the SIM-card out. It's important that the SIM card IS NOT in the phone, during the following steps!!
Turn on your phone without the SIM-card
Enter #*7337#
Insert the new SIM-card, and see if it is unlocked -----------------------------------------------------------------------
SGH-M100
Enter *#9998*627837793# (The phone shows an error)
Enter *#9998*737# (The phone says "lock status")
Push the >/ (play/stop) button until the phone is showing the NCK/SPCK number.
Write the last 8 digits down on a piece of paper
Push exit
Enter #0111*XXXXXXXX# (where the X's are the 8 digits you wrote in step )
The display schould now say: "Personalization Cancelled"
Your Samsung phone is now unlocked.
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SGH-N500 SGH-N600 SGH-N620
Take the SIM-card out. It's important that the SIM card IS NOT in the phone, during the following steps!!
Turn on your phone without the SIM-card
Enter *2767*2878#
Insert the new SIM-card, and see if it is unlocked
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SGH-P400
Take the SIM-card out. It's important that the SIM card IS NOT in the phone, during the following steps!!
Turn on your phone without the SIM-card
Enter *2767*688# or #*7337#
Insert the new SIM-card, and see if it is unlocked

Remove the battery from the phone. Let it remain out of the phone for 10 minutes with the phone off. Replace the battery and turn the phone on.

This is a problem with the phone trying to read the SIM card after being in another phone. Be patient. It may take several minutes for the phone to read the SIM.

Take the SIM-card out. It's important that the SIM card IS NOT in the phone, during the following steps.

Turn on your phone without the SIM-card

Enter *2767*637#
Insert the new SIM-card, and see if it is unlocked

Please assist me unlock my LG KP215 mobile phone

1-Turn on the phone without sim card .
2-Pull off the battery cover and insert any non-accepted sim card (without turning off the handset)
3-Do full reset *2767*3855# , phone will reboot and goes to Menu .
4-Customize Sp-lock code *7465625*638*00000000*00000000#
5-Unlock your phone with new SP code #7465625*638*00000000#
6-Enjoy G600 unlocked

Please follow the instructions carefully! Following are the 12-point instructions to unlock your Samsung E250 phone:
1. First do a CUSTOM RESET by tying in:
*2767*2878#
(Phone may display foreign language – don't worry! The last digits after the * will appear as - - - -; this is normal)
2. Turn off your phone
3. Take the battery and SIM out of the phone
4. Take a wrong network SIM (a SIM the phone does not currently accept) and insert it ONLY HALF way in, so when you turn on the phone it won't detect the SIM. Very important so the phone won't ask for network password and will show "Insert SIM" message.
The process of inserting only half of the SIM. I advice you to take care and do it with a soft approach as you might not have done this before.

5. 2. Now put the battery in carfully behind the protruding SIM card and switch the phone on. The phone must show "Insert SIM" message.
6. 3. Without turning off the phone, now push the SIM card all the way in, at this stage the phone must continue to display the "Insert SIM" message with the WRONG SIM inside.
7. Now make a FULL RESET by typing: *2767*3855#

9. Change the NCK password to 8 zeros by typing: *7465625*638*00000000*00000000#
8. The phone should reboot working with "wrong" SIM inside. (Do not turn off the phone)
10. Disable network lock by typing: #7465625*638*00000000#
12. Check this is done with *#7465625#
If your phone is not unlocked please retry the above ensuring all steps are followed to the letter, 9 out of 10 people who have problems have made a simple error and find that when they repeat all the steps it works.