My dad gave me his Nexus 4 to look at the other day because his phone is running slow and using up power very quick . I saw it has been installed couple of suspicious apps like gaining root permission, mobile assistant etc, can't remember the names cause I did a factory reset immediately (already backup the data). Ok it should be clean but then I saw a update notification (it's still on 4.4.3) so go upgrade. The phone reboot into upgrading interface, but after a while it showed 'Error' with a dead robot. I can restart the phone and it's sill in 4.4.3 and ok to use but just can't upgrade. I am thinking those apps must have done something otherwise the phone should be good to upgrade after a factory reset. I am thinking some app may have started a upgrade but somehow never finished (not sure, just my feeling). BTW, my dad knows nothing regarding these apps, they were probably installed by my nephew when he was visiting my parents. Any idea?