This is crazy.. My phone was locked after my 7 years old cousin tried a lot of patterns on my Dell xcd35, I tried unlocking it with my google account but Its crazy that it will never sign in if you have your wifi and data both are disabled. And you can even enable them because you are locked.
So I tried googling if there is a way out and found this video on youtube. It looked crazy.. I tried it on my phone too but dint work out though there were lots of comments that it worked on their phones. May be u should give it a try 😀
For my Dell XCD35 I had rooted the phone already with universal androot.
Careful, Dell XCD35 aka ZTE Blade consist of 2 generation, 1st generation is older and 2nd generation newer. (to find out, install Ask Mr Pigfish)
Flashing a ROM for one type on the other type will end up with a non-booting phone. So be sure which Gen is yours.
After rooting I had installed Clockwork for more info on this plese refer to this page.
With clockwork you can wipe, install new ROM from SDCard, backup current ROM and restore the backuped ROMS. Its really cool.