Trouble after un-jailbreaking iphone 4
I recently bought an iphone 4 locked to a Vodafone UK network which had an tethered jailbreak on 5.1 and came with cydia on it.
I'm not sure what Modem Firmware it was before that, but apparently I've inadvertently updated it. Right now it's
iPhone version 5.1 (9B176)
Modem Firmware (04.12.01)
I bought it thinking I knew enough about it to restore it to an un-jailbroken state. When I restored it to factory settings using iTunes, the jailbreak seemed gone but since then I've been unable to use my legit vodafone microSIM on it. It recognises the vodafone SIM but just refuses to pick up a signal. The bars are all flat. When I insert the vodafone SIM on another vodafone iphone, it picks up the signal alright.
Please help as I've spent a sum on it for me and this has practically ruined my holiday.