'Update.zip' is 'incorrect' - Blu Grand Max stuck after factory reset - can't get past system update on startup

I've been having malware issues with my Blu Grand Max and also it couldn't install a system update due to the file 'update.zip' being 'incorrect'.

I've tried a factory reset before (which didn't sort the malware), but decided to have another try today. After resetting the phone I'm now stuck on the startup process.

It's saying there's an update so the phone needs to be restarted - this is the same update that it couldn't install before - so therefore just returns to the Android Recovery screen with the error message. It doesn't show a skip button to bypass the update.

Is there any way I can download the update to sd card and install from the Recovery screen? If so, where do I download this from?

Thanks for your help.

I asked this on another forum as well and was advised to reinstall the stock ROM and this website was suggested for a guide on how to do it: (as a new user it won't let me post a link so just copy this and remove the spaces w w w . getdroidtips . c o m /stock-rom-blu-grand-max/.

I haven't got round to trying it yet, though I will do - just need some time to go through the instructions to make sure I know what I'm doing. The phone is useless at the minute so I can't mess it up any more even if I do something wrong.