Help Can't update to 2.3.5 - modified system software???

[jurat]

Whenever I try to update to 2.3.5 it gives me the modified system error. I just got this phone(2nd hand) and I come from iOS so I don't understand anything

 

[Caro332]

Click on fastboot, it will then give you a couple of other options and one of them should be reboot. Click on that.
Hopefully it should reboot again properly.
Otherwise if this doesn't work, would you know if the phone is s-off or rooted? I can't really make out the picture it's a bit blurry

 

[CafeKampuchia]

Whenever I try to update to 2.3.5 it gives me the modified system error. I just got this phone(2nd hand) and I come from iOS so I don't understand anything

What method are you using to try to update the ROM to 2.3.5?