LG Optimus black shows "No SIM inserted"

[Ramanujan]

My new LG shows that "No SIM inserted" . it is kind of strange problem. Do you think that it is a SIM or network lock or any other? Is there any way to fix this thing? AS far as i am concern i didnt buy any locked one. it was supposed to be a unlocked one. I dont know what is wrong with this thing?

[GracieSingh]

Restore the original ROM

• Run "B2CAppSetup"
• Remove the phone battery
• Hold down "vol +" and connect it via USB to the PC (on the screen of Black, it should have the message "S / W Upgrade - Please wait while upgrading ...")
• In "B2CAppSetup" (after he recognized the phone: "Phone connected"): click on "Customer Support" -> "SOS Recovery Mode"
• Insert your IMEI without the '-' (found on the box and / or in the location of the battery) and then "check" then "OK"
• The program will load the ROM and install it (internet connection required), it takes + / - 15 min

[Savannah87]

A friend had a similar problem with his cell phone, a piece of cardboard between the battery and SIM card (so that the card is pressed firmly on the contacts) works wonders.