Blackberry 9720 wont turn on red light blinking

Signal is not required to unlock a Blackberry 9720. All you need is a non accepted SIM card. Once you enter a non accepted SIM card in your Blackberry 9720, it would prompt you to enter an unlock code. You can get the accurate unlock code for a Blackberry 9720 from SuperUnlockCodes.com at affordable cost. Good luck.

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..............UNLOCKING INSTRUCTIONS..............
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1 - Switch ON your Blackberry 9720 with your current network/service provider's SIM card.
2 - Using the menu go to Settings Menu -> SIM card and press select.
3 - While holding the SHIFT key, type mepd.(NOTE: You may not see any text appear on the screen while typing mepd)
4 - You should now see the five locking categories listed.
5 - While holding the SHIFT KEY, type mep2.(NOTE: You may not see any text appear on the screen while typing mep2).
6 - Release the shift key.
7 - You will now be prompted to enter the Network MEP code. (it will also state how many attempts left)
8 - Enter the Unlock Code.
9 - Enter Return/Enter.
10 - The Blackberry 9720 should then be unlocked.

try getting a new battery or take it back to blackberry service center

Hi Michelle. I have the same phone and it happened to me a few times. On most phones the battery swells up when it reaches it's charging life end. In the 9720 the battery can still LOOK okay even though it might have reached its life-span. I eventually purchased a new battery, and wholaa, problem solved. A piece of additional advice is: Do not chat with you phone on the charger. Unplug the charger when battery is fully charged: We tend to charge the phone anytime and every time before we go to work or somewhere - you have to let the battery run flat on its own at least once a month, then start a fresh charge from fully flat to fully charged. This will prolong battery life. I a new battery does not solve the problem, have the charging pin checked out. Alternately if you know someone that has the same handset as you, ask them to stick your battery into their handset and visa versa. Hope this info help :)

The is needs to be flashed. Take it to a repair shop

Sounds like your BB is nuked/bricked. Follow this guide to get ir working again. http://crackberry.com/blackberry-101-lecture-12-how-reload-operating-system-nuked-blackberry

The blinking red lights are an indication that your phone battery is drained and needs to be charged before the phone can switch on. There's nothing wrong with your phone.

is any Red Blink at your Phone ?
if yes you can see the Red Blink (light with Red Color Blinking)
you must Flash/Upgrade Firmware your Blackberry.

I just called Verizon Wireless who said that the phone may need to be charged completely for a few hours. Try taking the battery out and putting it back on as well.

Red light usually means low battery so leave it for a hour or so red light should stop.