No Network symbol on Lumia 820

[Chris Sandiford]

Hi

I have just changed the LCD screen on my old Lumia 820 to sell on eBay.
Now it's all back together and working, it is saying that the SIM card is not recognised and there is a No Service icon on the Phone tile.

I can't see how the disassembly and repair of the screen is related, it must be just coincidence.

I have tried another SIM in it on the same network (O2 UK) and it's still the same.
I've tried a hard reset and reboot also.

Anyone got any advice?

Thanks.